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-rw-r--r--contrib/amcheck/.gitignore4
-rw-r--r--contrib/amcheck/Makefile27
-rw-r--r--contrib/amcheck/amcheck--1.0--1.1.sql29
-rw-r--r--contrib/amcheck/amcheck--1.0.sql24
-rw-r--r--contrib/amcheck/amcheck--1.1--1.2.sql19
-rw-r--r--contrib/amcheck/amcheck--1.2--1.3.sql30
-rw-r--r--contrib/amcheck/amcheck.control5
-rw-r--r--contrib/amcheck/expected/check.out1
-rw-r--r--contrib/amcheck/expected/check_btree.out210
-rw-r--r--contrib/amcheck/expected/check_heap.out201
-rw-r--r--contrib/amcheck/sql/check.sql1
-rw-r--r--contrib/amcheck/sql/check_btree.sql146
-rw-r--r--contrib/amcheck/sql/check_heap.sql116
-rw-r--r--contrib/amcheck/t/001_verify_heapam.pl286
-rw-r--r--contrib/amcheck/t/002_cic.pl64
-rw-r--r--contrib/amcheck/t/003_cic_2pc.pl187
-rw-r--r--contrib/amcheck/t/005_pitr.pl83
-rw-r--r--contrib/amcheck/verify_heapam.c1782
-rw-r--r--contrib/amcheck/verify_nbtree.c3346
19 files changed, 6561 insertions, 0 deletions
diff --git a/contrib/amcheck/.gitignore b/contrib/amcheck/.gitignore
new file mode 100644
index 0000000..5dcb3ff
--- /dev/null
+++ b/contrib/amcheck/.gitignore
@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/
diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
new file mode 100644
index 0000000..f830bd3
--- /dev/null
+++ b/contrib/amcheck/Makefile
@@ -0,0 +1,27 @@
+# contrib/amcheck/Makefile
+
+MODULE_big = amcheck
+OBJS = \
+ $(WIN32RES) \
+ verify_heapam.o \
+ verify_nbtree.o
+
+EXTENSION = amcheck
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+PGFILEDESC = "amcheck - function for verifying relation integrity"
+
+REGRESS = check check_btree check_heap
+
+EXTRA_INSTALL = contrib/pg_walinspect
+TAP_TESTS = 1
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/amcheck
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/contrib/amcheck/amcheck--1.0--1.1.sql b/contrib/amcheck/amcheck--1.0--1.1.sql
new file mode 100644
index 0000000..088416e
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.0--1.1.sql
@@ -0,0 +1,29 @@
+/* contrib/amcheck/amcheck--1.0--1.1.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.1'" to load this file. \quit
+
+-- In order to avoid issues with dependencies when updating amcheck to 1.1,
+-- create new, overloaded versions of the 1.0 functions
+
+--
+-- bt_index_check()
+--
+CREATE FUNCTION bt_index_check(index regclass,
+ heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'bt_index_check'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+--
+-- bt_index_parent_check()
+--
+CREATE FUNCTION bt_index_parent_check(index regclass,
+ heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'bt_index_parent_check'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+-- Don't want these to be available to public
+REVOKE ALL ON FUNCTION bt_index_check(regclass, boolean) FROM PUBLIC;
+REVOKE ALL ON FUNCTION bt_index_parent_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck--1.0.sql b/contrib/amcheck/amcheck--1.0.sql
new file mode 100644
index 0000000..a6612d1
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.0.sql
@@ -0,0 +1,24 @@
+/* contrib/amcheck/amcheck--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION amcheck" to load this file. \quit
+
+--
+-- bt_index_check()
+--
+CREATE FUNCTION bt_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'bt_index_check'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+--
+-- bt_index_parent_check()
+--
+CREATE FUNCTION bt_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'bt_index_parent_check'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+-- Don't want these to be available to public
+REVOKE ALL ON FUNCTION bt_index_check(regclass) FROM PUBLIC;
+REVOKE ALL ON FUNCTION bt_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck--1.1--1.2.sql b/contrib/amcheck/amcheck--1.1--1.2.sql
new file mode 100644
index 0000000..883530d
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.1--1.2.sql
@@ -0,0 +1,19 @@
+/* contrib/amcheck/amcheck--1.1--1.2.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.2'" to load this file. \quit
+
+-- In order to avoid issues with dependencies when updating amcheck to 1.2,
+-- create new, overloaded version of the 1.1 function signature
+
+--
+-- bt_index_parent_check()
+--
+CREATE FUNCTION bt_index_parent_check(index regclass,
+ heapallindexed boolean, rootdescend boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'bt_index_parent_check'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+-- Don't want this to be available to public
+REVOKE ALL ON FUNCTION bt_index_parent_check(regclass, boolean, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck--1.2--1.3.sql b/contrib/amcheck/amcheck--1.2--1.3.sql
new file mode 100644
index 0000000..7237ab7
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.2--1.3.sql
@@ -0,0 +1,30 @@
+/* contrib/amcheck/amcheck--1.2--1.3.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.3'" to load this file. \quit
+
+--
+-- verify_heapam()
+--
+CREATE FUNCTION verify_heapam(relation regclass,
+ on_error_stop boolean default false,
+ check_toast boolean default false,
+ skip text default 'none',
+ startblock bigint default null,
+ endblock bigint default null,
+ blkno OUT bigint,
+ offnum OUT integer,
+ attnum OUT integer,
+ msg OUT text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'verify_heapam'
+LANGUAGE C;
+
+-- Don't want this to be available to public
+REVOKE ALL ON FUNCTION verify_heapam(regclass,
+ boolean,
+ boolean,
+ text,
+ bigint,
+ bigint)
+FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
new file mode 100644
index 0000000..ab50931
--- /dev/null
+++ b/contrib/amcheck/amcheck.control
@@ -0,0 +1,5 @@
+# amcheck extension
+comment = 'functions for verifying relation integrity'
+default_version = '1.3'
+module_pathname = '$libdir/amcheck'
+relocatable = true
diff --git a/contrib/amcheck/expected/check.out b/contrib/amcheck/expected/check.out
new file mode 100644
index 0000000..5b3e6d5
--- /dev/null
+++ b/contrib/amcheck/expected/check.out
@@ -0,0 +1 @@
+CREATE EXTENSION amcheck;
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
new file mode 100644
index 0000000..38791bb
--- /dev/null
+++ b/contrib/amcheck/expected/check_btree.out
@@ -0,0 +1,210 @@
+CREATE TABLE bttest_a(id int8);
+CREATE TABLE bttest_b(id int8);
+CREATE TABLE bttest_multi(id int8, data int8);
+CREATE TABLE delete_test_table (a bigint, b bigint, c bigint, d bigint);
+-- Stabalize tests
+ALTER TABLE bttest_a SET (autovacuum_enabled = false);
+ALTER TABLE bttest_b SET (autovacuum_enabled = false);
+ALTER TABLE bttest_multi SET (autovacuum_enabled = false);
+ALTER TABLE delete_test_table SET (autovacuum_enabled = false);
+INSERT INTO bttest_a SELECT * FROM generate_series(1, 100000);
+INSERT INTO bttest_b SELECT * FROM generate_series(100000, 1, -1);
+INSERT INTO bttest_multi SELECT i, i%2 FROM generate_series(1, 100000) as i;
+CREATE INDEX bttest_a_idx ON bttest_a USING btree (id) WITH (deduplicate_items = ON);
+CREATE INDEX bttest_b_idx ON bttest_b USING btree (id);
+CREATE UNIQUE INDEX bttest_multi_idx ON bttest_multi
+USING btree (id) INCLUDE (data);
+CREATE ROLE regress_bttest_role;
+-- verify permissions are checked (error due to function not callable)
+SET ROLE regress_bttest_role;
+SELECT bt_index_check('bttest_a_idx'::regclass);
+ERROR: permission denied for function bt_index_check
+SELECT bt_index_parent_check('bttest_a_idx'::regclass);
+ERROR: permission denied for function bt_index_parent_check
+RESET ROLE;
+-- we, intentionally, don't check relation permissions - it's useful
+-- to run this cluster-wide with a restricted account, and as tested
+-- above explicit permission has to be granted for that.
+GRANT EXECUTE ON FUNCTION bt_index_check(regclass) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_check(regclass, boolean) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass, boolean) TO regress_bttest_role;
+SET ROLE regress_bttest_role;
+SELECT bt_index_check('bttest_a_idx');
+ bt_index_check
+----------------
+
+(1 row)
+
+SELECT bt_index_parent_check('bttest_a_idx');
+ bt_index_parent_check
+-----------------------
+
+(1 row)
+
+RESET ROLE;
+-- verify plain tables are rejected (error)
+SELECT bt_index_check('bttest_a');
+ERROR: "bttest_a" is not an index
+SELECT bt_index_parent_check('bttest_a');
+ERROR: "bttest_a" is not an index
+-- verify non-existing indexes are rejected (error)
+SELECT bt_index_check(17);
+ERROR: could not open relation with OID 17
+SELECT bt_index_parent_check(17);
+ERROR: could not open relation with OID 17
+-- verify wrong index types are rejected (error)
+BEGIN;
+CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
+SELECT bt_index_parent_check('bttest_a_brin_idx');
+ERROR: only B-Tree indexes are supported as targets for verification
+DETAIL: Relation "bttest_a_brin_idx" is not a B-Tree index.
+ROLLBACK;
+-- normal check outside of xact
+SELECT bt_index_check('bttest_a_idx');
+ bt_index_check
+----------------
+
+(1 row)
+
+-- more expansive tests
+SELECT bt_index_check('bttest_a_idx', true);
+ bt_index_check
+----------------
+
+(1 row)
+
+SELECT bt_index_parent_check('bttest_b_idx', true);
+ bt_index_parent_check
+-----------------------
+
+(1 row)
+
+BEGIN;
+SELECT bt_index_check('bttest_a_idx');
+ bt_index_check
+----------------
+
+(1 row)
+
+SELECT bt_index_parent_check('bttest_b_idx');
+ bt_index_parent_check
+-----------------------
+
+(1 row)
+
+-- make sure we don't have any leftover locks
+SELECT * FROM pg_locks
+WHERE relation = ANY(ARRAY['bttest_a', 'bttest_a_idx', 'bttest_b', 'bttest_b_idx']::regclass[])
+ AND pid = pg_backend_pid();
+ locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted | fastpath | waitstart
+----------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+-----+------+---------+----------+-----------
+(0 rows)
+
+COMMIT;
+-- Deduplication
+TRUNCATE bttest_a;
+INSERT INTO bttest_a SELECT 42 FROM generate_series(1, 2000);
+SELECT bt_index_check('bttest_a_idx', true);
+ bt_index_check
+----------------
+
+(1 row)
+
+-- normal check outside of xact for index with included columns
+SELECT bt_index_check('bttest_multi_idx');
+ bt_index_check
+----------------
+
+(1 row)
+
+-- more expansive tests for index with included columns
+SELECT bt_index_parent_check('bttest_multi_idx', true, true);
+ bt_index_parent_check
+-----------------------
+
+(1 row)
+
+-- repeat expansive tests for index built using insertions
+TRUNCATE bttest_multi;
+INSERT INTO bttest_multi SELECT i, i%2 FROM generate_series(1, 100000) as i;
+SELECT bt_index_parent_check('bttest_multi_idx', true, true);
+ bt_index_parent_check
+-----------------------
+
+(1 row)
+
+--
+-- Test for multilevel page deletion/downlink present checks, and rootdescend
+-- checks
+--
+INSERT INTO delete_test_table SELECT i, 1, 2, 3 FROM generate_series(1,80000) i;
+ALTER TABLE delete_test_table ADD PRIMARY KEY (a,b,c,d);
+-- Delete most entries, and vacuum, deleting internal pages and creating "fast
+-- root"
+DELETE FROM delete_test_table WHERE a < 79990;
+VACUUM delete_test_table;
+SELECT bt_index_parent_check('delete_test_table_pkey', true);
+ bt_index_parent_check
+-----------------------
+
+(1 row)
+
+--
+-- BUG #15597: must not assume consistent input toasting state when forming
+-- tuple. Bloom filter must fingerprint normalized index tuple representation.
+--
+CREATE TABLE toast_bug(buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT bt_index_check('toasty', true);
+ bt_index_check
+----------------
+
+(1 row)
+
+--
+-- Check that index expressions and predicates are run as the table's owner
+--
+TRUNCATE bttest_a;
+INSERT INTO bttest_a SELECT * FROM generate_series(1, 1000);
+ALTER TABLE bttest_a OWNER TO regress_bttest_role;
+-- A dummy index function checking current_user
+CREATE FUNCTION ifun(int8) RETURNS int8 AS $$
+BEGIN
+ ASSERT current_user = 'regress_bttest_role',
+ format('ifun(%s) called by %s', $1, current_user);
+ RETURN $1;
+END;
+$$ LANGUAGE plpgsql IMMUTABLE;
+CREATE INDEX bttest_a_expr_idx ON bttest_a ((ifun(id) + ifun(0)))
+ WHERE ifun(id + 10) > ifun(10);
+SELECT bt_index_check('bttest_a_expr_idx', true);
+ bt_index_check
+----------------
+
+(1 row)
+
+-- cleanup
+DROP TABLE bttest_a;
+DROP TABLE bttest_b;
+DROP TABLE bttest_multi;
+DROP TABLE delete_test_table;
+DROP TABLE toast_bug;
+DROP FUNCTION ifun(int8);
+DROP OWNED BY regress_bttest_role; -- permissions
+DROP ROLE regress_bttest_role;
diff --git a/contrib/amcheck/expected/check_heap.out b/contrib/amcheck/expected/check_heap.out
new file mode 100644
index 0000000..c010361
--- /dev/null
+++ b/contrib/amcheck/expected/check_heap.out
@@ -0,0 +1,201 @@
+CREATE TABLE heaptest (a integer, b text);
+REVOKE ALL ON heaptest FROM PUBLIC;
+-- Check that invalid skip option is rejected
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'rope');
+ERROR: invalid skip option
+HINT: Valid skip options are "all-visible", "all-frozen", and "none".
+-- Check specifying invalid block ranges when verifying an empty table
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 0);
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 5, endblock := 8);
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+-- Check that valid options are not rejected nor corruption reported
+-- for an empty table, and that skip enum-like parameter is case-insensitive
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'none');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-frozen');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-visible');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'None');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'All-Frozen');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'All-Visible');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'NONE');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'ALL-FROZEN');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'ALL-VISIBLE');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+-- Add some data so subsequent tests are not entirely trivial
+INSERT INTO heaptest (a, b)
+ (SELECT gs, repeat('x', gs)
+ FROM generate_series(1,50) gs);
+-- Check that valid options are not rejected nor corruption reported
+-- for a non-empty table
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'none');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-frozen');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-visible');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 0);
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+CREATE ROLE regress_heaptest_role;
+-- verify permissions are checked (error due to function not callable)
+SET ROLE regress_heaptest_role;
+SELECT * FROM verify_heapam(relation := 'heaptest');
+ERROR: permission denied for function verify_heapam
+RESET ROLE;
+GRANT EXECUTE ON FUNCTION verify_heapam(regclass, boolean, boolean, text, bigint, bigint) TO regress_heaptest_role;
+-- verify permissions are now sufficient
+SET ROLE regress_heaptest_role;
+SELECT * FROM verify_heapam(relation := 'heaptest');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+RESET ROLE;
+-- Check specifying invalid block ranges when verifying a non-empty table.
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 10000);
+ERROR: ending block number must be between 0 and 0
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 10000, endblock := 11000);
+ERROR: starting block number must be between 0 and 0
+-- Vacuum freeze to change the xids encountered in subsequent tests
+VACUUM (FREEZE, DISABLE_PAGE_SKIPPING) heaptest;
+-- Check that valid options are not rejected nor corruption reported
+-- for a non-empty frozen table
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'none');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-frozen');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-visible');
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 0);
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+-- Check that partitioned tables (the parent ones) which don't have visibility
+-- maps are rejected
+CREATE TABLE test_partitioned (a int, b text default repeat('x', 5000))
+ PARTITION BY list (a);
+SELECT * FROM verify_heapam('test_partitioned',
+ startblock := NULL,
+ endblock := NULL);
+ERROR: cannot check relation "test_partitioned"
+DETAIL: This operation is not supported for partitioned tables.
+-- Check that valid options are not rejected nor corruption reported
+-- for an empty partition table (the child one)
+CREATE TABLE test_partition partition OF test_partitioned FOR VALUES IN (1);
+SELECT * FROM verify_heapam('test_partition',
+ startblock := NULL,
+ endblock := NULL);
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+-- Check that valid options are not rejected nor corruption reported
+-- for a non-empty partition table (the child one)
+INSERT INTO test_partitioned (a) (SELECT 1 FROM generate_series(1,1000) gs);
+SELECT * FROM verify_heapam('test_partition',
+ startblock := NULL,
+ endblock := NULL);
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+-- Check that indexes are rejected
+CREATE INDEX test_index ON test_partition (a);
+SELECT * FROM verify_heapam('test_index',
+ startblock := NULL,
+ endblock := NULL);
+ERROR: cannot check relation "test_index"
+DETAIL: This operation is not supported for indexes.
+-- Check that views are rejected
+CREATE VIEW test_view AS SELECT 1;
+SELECT * FROM verify_heapam('test_view',
+ startblock := NULL,
+ endblock := NULL);
+ERROR: cannot check relation "test_view"
+DETAIL: This operation is not supported for views.
+-- Check that sequences are rejected
+CREATE SEQUENCE test_sequence;
+SELECT * FROM verify_heapam('test_sequence',
+ startblock := NULL,
+ endblock := NULL);
+ blkno | offnum | attnum | msg
+-------+--------+--------+-----
+(0 rows)
+
+-- Check that foreign tables are rejected
+CREATE FOREIGN DATA WRAPPER dummy;
+CREATE SERVER dummy_server FOREIGN DATA WRAPPER dummy;
+CREATE FOREIGN TABLE test_foreign_table () SERVER dummy_server;
+SELECT * FROM verify_heapam('test_foreign_table',
+ startblock := NULL,
+ endblock := NULL);
+ERROR: cannot check relation "test_foreign_table"
+DETAIL: This operation is not supported for foreign tables.
+-- cleanup
+DROP TABLE heaptest;
+DROP TABLE test_partition;
+DROP TABLE test_partitioned;
+DROP OWNED BY regress_heaptest_role; -- permissions
+DROP ROLE regress_heaptest_role;
diff --git a/contrib/amcheck/sql/check.sql b/contrib/amcheck/sql/check.sql
new file mode 100644
index 0000000..5b3e6d5
--- /dev/null
+++ b/contrib/amcheck/sql/check.sql
@@ -0,0 +1 @@
+CREATE EXTENSION amcheck;
diff --git a/contrib/amcheck/sql/check_btree.sql b/contrib/amcheck/sql/check_btree.sql
new file mode 100644
index 0000000..033c04b
--- /dev/null
+++ b/contrib/amcheck/sql/check_btree.sql
@@ -0,0 +1,146 @@
+CREATE TABLE bttest_a(id int8);
+CREATE TABLE bttest_b(id int8);
+CREATE TABLE bttest_multi(id int8, data int8);
+CREATE TABLE delete_test_table (a bigint, b bigint, c bigint, d bigint);
+
+-- Stabalize tests
+ALTER TABLE bttest_a SET (autovacuum_enabled = false);
+ALTER TABLE bttest_b SET (autovacuum_enabled = false);
+ALTER TABLE bttest_multi SET (autovacuum_enabled = false);
+ALTER TABLE delete_test_table SET (autovacuum_enabled = false);
+
+INSERT INTO bttest_a SELECT * FROM generate_series(1, 100000);
+INSERT INTO bttest_b SELECT * FROM generate_series(100000, 1, -1);
+INSERT INTO bttest_multi SELECT i, i%2 FROM generate_series(1, 100000) as i;
+
+CREATE INDEX bttest_a_idx ON bttest_a USING btree (id) WITH (deduplicate_items = ON);
+CREATE INDEX bttest_b_idx ON bttest_b USING btree (id);
+CREATE UNIQUE INDEX bttest_multi_idx ON bttest_multi
+USING btree (id) INCLUDE (data);
+
+CREATE ROLE regress_bttest_role;
+
+-- verify permissions are checked (error due to function not callable)
+SET ROLE regress_bttest_role;
+SELECT bt_index_check('bttest_a_idx'::regclass);
+SELECT bt_index_parent_check('bttest_a_idx'::regclass);
+RESET ROLE;
+
+-- we, intentionally, don't check relation permissions - it's useful
+-- to run this cluster-wide with a restricted account, and as tested
+-- above explicit permission has to be granted for that.
+GRANT EXECUTE ON FUNCTION bt_index_check(regclass) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_check(regclass, boolean) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass, boolean) TO regress_bttest_role;
+SET ROLE regress_bttest_role;
+SELECT bt_index_check('bttest_a_idx');
+SELECT bt_index_parent_check('bttest_a_idx');
+RESET ROLE;
+
+-- verify plain tables are rejected (error)
+SELECT bt_index_check('bttest_a');
+SELECT bt_index_parent_check('bttest_a');
+
+-- verify non-existing indexes are rejected (error)
+SELECT bt_index_check(17);
+SELECT bt_index_parent_check(17);
+
+-- verify wrong index types are rejected (error)
+BEGIN;
+CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
+SELECT bt_index_parent_check('bttest_a_brin_idx');
+ROLLBACK;
+
+-- normal check outside of xact
+SELECT bt_index_check('bttest_a_idx');
+-- more expansive tests
+SELECT bt_index_check('bttest_a_idx', true);
+SELECT bt_index_parent_check('bttest_b_idx', true);
+
+BEGIN;
+SELECT bt_index_check('bttest_a_idx');
+SELECT bt_index_parent_check('bttest_b_idx');
+-- make sure we don't have any leftover locks
+SELECT * FROM pg_locks
+WHERE relation = ANY(ARRAY['bttest_a', 'bttest_a_idx', 'bttest_b', 'bttest_b_idx']::regclass[])
+ AND pid = pg_backend_pid();
+COMMIT;
+
+-- Deduplication
+TRUNCATE bttest_a;
+INSERT INTO bttest_a SELECT 42 FROM generate_series(1, 2000);
+SELECT bt_index_check('bttest_a_idx', true);
+
+-- normal check outside of xact for index with included columns
+SELECT bt_index_check('bttest_multi_idx');
+-- more expansive tests for index with included columns
+SELECT bt_index_parent_check('bttest_multi_idx', true, true);
+
+-- repeat expansive tests for index built using insertions
+TRUNCATE bttest_multi;
+INSERT INTO bttest_multi SELECT i, i%2 FROM generate_series(1, 100000) as i;
+SELECT bt_index_parent_check('bttest_multi_idx', true, true);
+
+--
+-- Test for multilevel page deletion/downlink present checks, and rootdescend
+-- checks
+--
+INSERT INTO delete_test_table SELECT i, 1, 2, 3 FROM generate_series(1,80000) i;
+ALTER TABLE delete_test_table ADD PRIMARY KEY (a,b,c,d);
+-- Delete most entries, and vacuum, deleting internal pages and creating "fast
+-- root"
+DELETE FROM delete_test_table WHERE a < 79990;
+VACUUM delete_test_table;
+SELECT bt_index_parent_check('delete_test_table_pkey', true);
+
+--
+-- BUG #15597: must not assume consistent input toasting state when forming
+-- tuple. Bloom filter must fingerprint normalized index tuple representation.
+--
+CREATE TABLE toast_bug(buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT bt_index_check('toasty', true);
+
+--
+-- Check that index expressions and predicates are run as the table's owner
+--
+TRUNCATE bttest_a;
+INSERT INTO bttest_a SELECT * FROM generate_series(1, 1000);
+ALTER TABLE bttest_a OWNER TO regress_bttest_role;
+-- A dummy index function checking current_user
+CREATE FUNCTION ifun(int8) RETURNS int8 AS $$
+BEGIN
+ ASSERT current_user = 'regress_bttest_role',
+ format('ifun(%s) called by %s', $1, current_user);
+ RETURN $1;
+END;
+$$ LANGUAGE plpgsql IMMUTABLE;
+
+CREATE INDEX bttest_a_expr_idx ON bttest_a ((ifun(id) + ifun(0)))
+ WHERE ifun(id + 10) > ifun(10);
+
+SELECT bt_index_check('bttest_a_expr_idx', true);
+
+-- cleanup
+DROP TABLE bttest_a;
+DROP TABLE bttest_b;
+DROP TABLE bttest_multi;
+DROP TABLE delete_test_table;
+DROP TABLE toast_bug;
+DROP FUNCTION ifun(int8);
+DROP OWNED BY regress_bttest_role; -- permissions
+DROP ROLE regress_bttest_role;
diff --git a/contrib/amcheck/sql/check_heap.sql b/contrib/amcheck/sql/check_heap.sql
new file mode 100644
index 0000000..298de68
--- /dev/null
+++ b/contrib/amcheck/sql/check_heap.sql
@@ -0,0 +1,116 @@
+CREATE TABLE heaptest (a integer, b text);
+REVOKE ALL ON heaptest FROM PUBLIC;
+
+-- Check that invalid skip option is rejected
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'rope');
+
+-- Check specifying invalid block ranges when verifying an empty table
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 0);
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 5, endblock := 8);
+
+-- Check that valid options are not rejected nor corruption reported
+-- for an empty table, and that skip enum-like parameter is case-insensitive
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'none');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-frozen');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-visible');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'None');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'All-Frozen');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'All-Visible');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'NONE');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'ALL-FROZEN');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'ALL-VISIBLE');
+
+-- Add some data so subsequent tests are not entirely trivial
+INSERT INTO heaptest (a, b)
+ (SELECT gs, repeat('x', gs)
+ FROM generate_series(1,50) gs);
+
+-- Check that valid options are not rejected nor corruption reported
+-- for a non-empty table
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'none');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-frozen');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-visible');
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 0);
+
+CREATE ROLE regress_heaptest_role;
+
+-- verify permissions are checked (error due to function not callable)
+SET ROLE regress_heaptest_role;
+SELECT * FROM verify_heapam(relation := 'heaptest');
+RESET ROLE;
+
+GRANT EXECUTE ON FUNCTION verify_heapam(regclass, boolean, boolean, text, bigint, bigint) TO regress_heaptest_role;
+
+-- verify permissions are now sufficient
+SET ROLE regress_heaptest_role;
+SELECT * FROM verify_heapam(relation := 'heaptest');
+RESET ROLE;
+
+-- Check specifying invalid block ranges when verifying a non-empty table.
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 10000);
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 10000, endblock := 11000);
+
+-- Vacuum freeze to change the xids encountered in subsequent tests
+VACUUM (FREEZE, DISABLE_PAGE_SKIPPING) heaptest;
+
+-- Check that valid options are not rejected nor corruption reported
+-- for a non-empty frozen table
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'none');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-frozen');
+SELECT * FROM verify_heapam(relation := 'heaptest', skip := 'all-visible');
+SELECT * FROM verify_heapam(relation := 'heaptest', startblock := 0, endblock := 0);
+
+-- Check that partitioned tables (the parent ones) which don't have visibility
+-- maps are rejected
+CREATE TABLE test_partitioned (a int, b text default repeat('x', 5000))
+ PARTITION BY list (a);
+SELECT * FROM verify_heapam('test_partitioned',
+ startblock := NULL,
+ endblock := NULL);
+
+-- Check that valid options are not rejected nor corruption reported
+-- for an empty partition table (the child one)
+CREATE TABLE test_partition partition OF test_partitioned FOR VALUES IN (1);
+SELECT * FROM verify_heapam('test_partition',
+ startblock := NULL,
+ endblock := NULL);
+
+-- Check that valid options are not rejected nor corruption reported
+-- for a non-empty partition table (the child one)
+INSERT INTO test_partitioned (a) (SELECT 1 FROM generate_series(1,1000) gs);
+SELECT * FROM verify_heapam('test_partition',
+ startblock := NULL,
+ endblock := NULL);
+
+-- Check that indexes are rejected
+CREATE INDEX test_index ON test_partition (a);
+SELECT * FROM verify_heapam('test_index',
+ startblock := NULL,
+ endblock := NULL);
+
+-- Check that views are rejected
+CREATE VIEW test_view AS SELECT 1;
+SELECT * FROM verify_heapam('test_view',
+ startblock := NULL,
+ endblock := NULL);
+
+-- Check that sequences are rejected
+CREATE SEQUENCE test_sequence;
+SELECT * FROM verify_heapam('test_sequence',
+ startblock := NULL,
+ endblock := NULL);
+
+-- Check that foreign tables are rejected
+CREATE FOREIGN DATA WRAPPER dummy;
+CREATE SERVER dummy_server FOREIGN DATA WRAPPER dummy;
+CREATE FOREIGN TABLE test_foreign_table () SERVER dummy_server;
+SELECT * FROM verify_heapam('test_foreign_table',
+ startblock := NULL,
+ endblock := NULL);
+
+-- cleanup
+DROP TABLE heaptest;
+DROP TABLE test_partition;
+DROP TABLE test_partitioned;
+DROP OWNED BY regress_heaptest_role; -- permissions
+DROP ROLE regress_heaptest_role;
diff --git a/contrib/amcheck/t/001_verify_heapam.pl b/contrib/amcheck/t/001_verify_heapam.pl
new file mode 100644
index 0000000..019eed3
--- /dev/null
+++ b/contrib/amcheck/t/001_verify_heapam.pl
@@ -0,0 +1,286 @@
+
+# Copyright (c) 2021-2022, PostgreSQL Global Development Group
+
+use strict;
+use warnings;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my ($node, $result);
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init;
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+
+#
+# Check a table with data loaded but no corruption, freezing, etc.
+#
+fresh_test_table('test');
+check_all_options_uncorrupted('test', 'plain');
+
+#
+# Check a corrupt table
+#
+fresh_test_table('test');
+corrupt_first_page('test');
+detects_heap_corruption("verify_heapam('test')", "plain corrupted table");
+detects_heap_corruption(
+ "verify_heapam('test', skip := 'all-visible')",
+ "plain corrupted table skipping all-visible");
+detects_heap_corruption(
+ "verify_heapam('test', skip := 'all-frozen')",
+ "plain corrupted table skipping all-frozen");
+detects_heap_corruption(
+ "verify_heapam('test', check_toast := false)",
+ "plain corrupted table skipping toast");
+detects_heap_corruption(
+ "verify_heapam('test', startblock := 0, endblock := 0)",
+ "plain corrupted table checking only block zero");
+
+#
+# Check a corrupt table with all-frozen data
+#
+fresh_test_table('test');
+$node->safe_psql('postgres', q(VACUUM (FREEZE, DISABLE_PAGE_SKIPPING) test));
+detects_no_corruption("verify_heapam('test')",
+ "all-frozen not corrupted table");
+corrupt_first_page('test');
+detects_heap_corruption("verify_heapam('test')",
+ "all-frozen corrupted table");
+detects_no_corruption(
+ "verify_heapam('test', skip := 'all-frozen')",
+ "all-frozen corrupted table skipping all-frozen");
+
+#
+# Check a sequence with no corruption. The current implementation of sequences
+# doesn't require its own test setup, since sequences are really just heap
+# tables under-the-hood. To guard against future implementation changes made
+# without remembering to update verify_heapam, we create and exercise a
+# sequence, checking along the way that it passes corruption checks.
+#
+fresh_test_sequence('test_seq');
+check_all_options_uncorrupted('test_seq', 'plain');
+advance_test_sequence('test_seq');
+check_all_options_uncorrupted('test_seq', 'plain');
+set_test_sequence('test_seq');
+check_all_options_uncorrupted('test_seq', 'plain');
+reset_test_sequence('test_seq');
+check_all_options_uncorrupted('test_seq', 'plain');
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+ my ($relname) = @_;
+
+ my $pgdata = $node->data_dir;
+ my $rel = $node->safe_psql('postgres',
+ qq(SELECT pg_relation_filepath('$relname')));
+ die "path not found for relation $relname" unless defined $rel;
+ return "$pgdata/$rel";
+}
+
+# Returns the fully qualified name of the toast table for the named relation
+sub get_toast_for
+{
+ my ($relname) = @_;
+
+ return $node->safe_psql(
+ 'postgres', qq(
+ SELECT 'pg_toast.' || t.relname
+ FROM pg_catalog.pg_class c, pg_catalog.pg_class t
+ WHERE c.relname = '$relname'
+ AND c.reltoastrelid = t.oid));
+}
+
+# (Re)create and populate a test table of the given name.
+sub fresh_test_table
+{
+ my ($relname) = @_;
+
+ return $node->safe_psql(
+ 'postgres', qq(
+ DROP TABLE IF EXISTS $relname CASCADE;
+ CREATE TABLE $relname (a integer, b text);
+ ALTER TABLE $relname SET (autovacuum_enabled=false);
+ ALTER TABLE $relname ALTER b SET STORAGE external;
+ INSERT INTO $relname (a, b)
+ (SELECT gs, repeat('b',gs*10) FROM generate_series(1,1000) gs);
+ BEGIN;
+ SAVEPOINT s1;
+ SELECT 1 FROM $relname WHERE a = 42 FOR UPDATE;
+ UPDATE $relname SET b = b WHERE a = 42;
+ RELEASE s1;
+ SAVEPOINT s1;
+ SELECT 1 FROM $relname WHERE a = 42 FOR UPDATE;
+ UPDATE $relname SET b = b WHERE a = 42;
+ COMMIT;
+ ));
+}
+
+# Create a test sequence of the given name.
+sub fresh_test_sequence
+{
+ my ($seqname) = @_;
+
+ return $node->safe_psql(
+ 'postgres', qq(
+ DROP SEQUENCE IF EXISTS $seqname CASCADE;
+ CREATE SEQUENCE $seqname
+ INCREMENT BY 13
+ MINVALUE 17
+ START WITH 23;
+ SELECT nextval('$seqname');
+ SELECT setval('$seqname', currval('$seqname') + nextval('$seqname'));
+ ));
+}
+
+# Call SQL functions to increment the sequence
+sub advance_test_sequence
+{
+ my ($seqname) = @_;
+
+ return $node->safe_psql(
+ 'postgres', qq(
+ SELECT nextval('$seqname');
+ ));
+}
+
+# Call SQL functions to set the sequence
+sub set_test_sequence
+{
+ my ($seqname) = @_;
+
+ return $node->safe_psql(
+ 'postgres', qq(
+ SELECT setval('$seqname', 102);
+ ));
+}
+
+# Call SQL functions to reset the sequence
+sub reset_test_sequence
+{
+ my ($seqname) = @_;
+
+ return $node->safe_psql(
+ 'postgres', qq(
+ ALTER SEQUENCE $seqname RESTART WITH 51
+ ));
+}
+
+# Stops the test node, corrupts the first page of the named relation, and
+# restarts the node.
+sub corrupt_first_page
+{
+ my ($relname) = @_;
+ my $relpath = relation_filepath($relname);
+
+ $node->stop;
+
+ my $fh;
+ open($fh, '+<', $relpath)
+ or BAIL_OUT("open failed: $!");
+ binmode $fh;
+
+ # Corrupt some line pointers. The values are chosen to hit the
+ # various line-pointer-corruption checks in verify_heapam.c
+ # on both little-endian and big-endian architectures.
+ sysseek($fh, 32, 0)
+ or BAIL_OUT("sysseek failed: $!");
+ syswrite(
+ $fh,
+ pack("L*",
+ 0xAAA15550, 0xAAA0D550, 0x00010000,
+ 0x00008000, 0x0000800F, 0x001e8000)
+ ) or BAIL_OUT("syswrite failed: $!");
+ close($fh)
+ or BAIL_OUT("close failed: $!");
+
+ $node->start;
+}
+
+sub detects_heap_corruption
+{
+ local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+ my ($function, $testname) = @_;
+
+ detects_corruption(
+ $function,
+ $testname,
+ qr/line pointer redirection to item at offset \d+ precedes minimum offset \d+/,
+ qr/line pointer redirection to item at offset \d+ exceeds maximum offset \d+/,
+ qr/line pointer to page offset \d+ is not maximally aligned/,
+ qr/line pointer length \d+ is less than the minimum tuple header size \d+/,
+ qr/line pointer to page offset \d+ with length \d+ ends beyond maximum page offset \d+/,
+ );
+}
+
+sub detects_corruption
+{
+ local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+ my ($function, $testname, @re) = @_;
+
+ my $result = $node->safe_psql('postgres', qq(SELECT * FROM $function));
+ like($result, $_, $testname) for (@re);
+}
+
+sub detects_no_corruption
+{
+ local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+ my ($function, $testname) = @_;
+
+ my $result = $node->safe_psql('postgres', qq(SELECT * FROM $function));
+ is($result, '', $testname);
+}
+
+# Check various options are stable (don't abort) and do not report corruption
+# when running verify_heapam on an uncorrupted test table.
+#
+# The relname *must* be an uncorrupted table, or this will fail.
+#
+# The prefix is used to identify the test, along with the options,
+# and should be unique.
+sub check_all_options_uncorrupted
+{
+ local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+ my ($relname, $prefix) = @_;
+
+ for my $stop (qw(true false))
+ {
+ for my $check_toast (qw(true false))
+ {
+ for my $skip ("'none'", "'all-frozen'", "'all-visible'")
+ {
+ for my $startblock (qw(NULL 0))
+ {
+ for my $endblock (qw(NULL 0))
+ {
+ my $opts =
+ "on_error_stop := $stop, "
+ . "check_toast := $check_toast, "
+ . "skip := $skip, "
+ . "startblock := $startblock, "
+ . "endblock := $endblock";
+
+ detects_no_corruption(
+ "verify_heapam('$relname', $opts)",
+ "$prefix: $opts");
+ }
+ }
+ }
+ }
+ }
+}
+
+done_testing();
diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
new file mode 100644
index 0000000..32e4e4a
--- /dev/null
+++ b/contrib/amcheck/t/002_cic.pl
@@ -0,0 +1,64 @@
+
+# Copyright (c) 2021-2022, PostgreSQL Global Development Group
+
+# Test CREATE INDEX CONCURRENTLY with concurrent modifications
+use strict;
+use warnings;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my ($node, $result);
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('CIC_test');
+$node->init;
+$node->append_conf('postgresql.conf',
+ 'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i)));
+
+#
+# Stress CIC with pgbench.
+#
+# pgbench might try to launch more than one instance of the CIC
+# transaction concurrently. That would deadlock, so use an advisory
+# lock to ensure only one CIC runs at a time.
+#
+$node->pgbench(
+ '--no-vacuum --client=5 --transactions=100',
+ 0,
+ [qr{actually processed}],
+ [qr{^$}],
+ 'concurrent INSERTs and CIC',
+ {
+ '002_pgbench_concurrent_transaction' => q(
+ BEGIN;
+ INSERT INTO tbl VALUES(0);
+ COMMIT;
+ ),
+ '002_pgbench_concurrent_transaction_savepoints' => q(
+ BEGIN;
+ SAVEPOINT s1;
+ INSERT INTO tbl VALUES(0);
+ COMMIT;
+ ),
+ '002_pgbench_concurrent_cic' => q(
+ SELECT pg_try_advisory_lock(42)::integer AS gotlock \gset
+ \if :gotlock
+ DROP INDEX CONCURRENTLY idx;
+ CREATE INDEX CONCURRENTLY idx ON tbl(i);
+ SELECT bt_index_check('idx',true);
+ SELECT pg_advisory_unlock(42);
+ \endif
+ )
+ });
+
+$node->stop;
+done_testing();
diff --git a/contrib/amcheck/t/003_cic_2pc.pl b/contrib/amcheck/t/003_cic_2pc.pl
new file mode 100644
index 0000000..1a2ccea
--- /dev/null
+++ b/contrib/amcheck/t/003_cic_2pc.pl
@@ -0,0 +1,187 @@
+
+# Copyright (c) 2021-2022, PostgreSQL Global Development Group
+
+# Test CREATE INDEX CONCURRENTLY with concurrent prepared-xact modifications
+use strict;
+use warnings;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+Test::More->builder->todo_start('filesystem bug')
+ if PostgreSQL::Test::Utils::has_wal_read_bug;
+
+my ($node, $result);
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('CIC_2PC_test');
+$node->init;
+$node->append_conf('postgresql.conf', 'max_prepared_transactions = 10');
+$node->append_conf('postgresql.conf',
+ 'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+
+
+#
+# Run 3 overlapping 2PC transactions with CIC
+#
+# We have two concurrent background psql processes: $main_h for INSERTs and
+# $cic_h for CIC. Also, we use non-background psql for some COMMIT PREPARED
+# statements.
+#
+
+my $main_in = '';
+my $main_out = '';
+my $main_timer = IPC::Run::timeout($PostgreSQL::Test::Utils::timeout_default);
+
+my $main_h =
+ $node->background_psql('postgres', \$main_in, \$main_out,
+ $main_timer, on_error_stop => 1);
+$main_in .= q(
+BEGIN;
+INSERT INTO tbl VALUES(0);
+\echo syncpoint1
+);
+pump $main_h until $main_out =~ /syncpoint1/ || $main_timer->is_expired;
+
+my $cic_in = '';
+my $cic_out = '';
+my $cic_timer = IPC::Run::timeout($PostgreSQL::Test::Utils::timeout_default);
+my $cic_h =
+ $node->background_psql('postgres', \$cic_in, \$cic_out,
+ $cic_timer, on_error_stop => 1);
+$cic_in .= q(
+\echo start
+CREATE INDEX CONCURRENTLY idx ON tbl(i);
+);
+pump $cic_h until $cic_out =~ /start/ || $cic_timer->is_expired;
+
+$main_in .= q(
+PREPARE TRANSACTION 'a';
+);
+
+$main_in .= q(
+BEGIN;
+INSERT INTO tbl VALUES(0);
+\echo syncpoint2
+);
+pump $main_h until $main_out =~ /syncpoint2/ || $main_timer->is_expired;
+
+$node->safe_psql('postgres', q(COMMIT PREPARED 'a';));
+
+$main_in .= q(
+PREPARE TRANSACTION 'b';
+BEGIN;
+INSERT INTO tbl VALUES(0);
+\echo syncpoint3
+);
+pump $main_h until $main_out =~ /syncpoint3/ || $main_timer->is_expired;
+
+$node->safe_psql('postgres', q(COMMIT PREPARED 'b';));
+
+$main_in .= q(
+PREPARE TRANSACTION 'c';
+COMMIT PREPARED 'c';
+);
+$main_h->pump_nb;
+
+$main_h->finish;
+$cic_h->finish;
+
+$result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
+is($result, '0', 'bt_index_check after overlapping 2PC');
+
+
+#
+# Server restart shall not change whether prepared xact blocks CIC
+#
+
+$node->safe_psql(
+ 'postgres', q(
+BEGIN;
+INSERT INTO tbl VALUES(0);
+PREPARE TRANSACTION 'spans_restart';
+BEGIN;
+CREATE TABLE unused ();
+PREPARE TRANSACTION 'persists_forever';
+));
+$node->restart;
+
+my $reindex_in = '';
+my $reindex_out = '';
+my $reindex_timer =
+ IPC::Run::timeout($PostgreSQL::Test::Utils::timeout_default);
+my $reindex_h =
+ $node->background_psql('postgres', \$reindex_in, \$reindex_out,
+ $reindex_timer, on_error_stop => 1);
+$reindex_in .= q(
+\echo start
+DROP INDEX CONCURRENTLY idx;
+CREATE INDEX CONCURRENTLY idx ON tbl(i);
+);
+pump $reindex_h until $reindex_out =~ /start/ || $reindex_timer->is_expired;
+
+$node->safe_psql('postgres', "COMMIT PREPARED 'spans_restart'");
+$reindex_h->finish;
+$result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
+is($result, '0', 'bt_index_check after 2PC and restart');
+
+
+#
+# Stress CIC+2PC with pgbench
+#
+# pgbench might try to launch more than one instance of the CIC
+# transaction concurrently. That would deadlock, so use an advisory
+# lock to ensure only one CIC runs at a time.
+
+# Fix broken index first
+$node->safe_psql('postgres', q(REINDEX TABLE tbl;));
+
+# Run pgbench.
+$node->pgbench(
+ '--no-vacuum --client=5 --transactions=100',
+ 0,
+ [qr{actually processed}],
+ [qr{^$}],
+ 'concurrent INSERTs w/ 2PC and CIC',
+ {
+ '003_pgbench_concurrent_2pc' => q(
+ BEGIN;
+ INSERT INTO tbl VALUES(0);
+ PREPARE TRANSACTION 'c:client_id';
+ COMMIT PREPARED 'c:client_id';
+ ),
+ '003_pgbench_concurrent_2pc_savepoint' => q(
+ BEGIN;
+ SAVEPOINT s1;
+ INSERT INTO tbl VALUES(0);
+ PREPARE TRANSACTION 'c:client_id';
+ COMMIT PREPARED 'c:client_id';
+ ),
+ '003_pgbench_concurrent_cic' => q(
+ SELECT pg_try_advisory_lock(42)::integer AS gotlock \gset
+ \if :gotlock
+ DROP INDEX CONCURRENTLY idx;
+ CREATE INDEX CONCURRENTLY idx ON tbl(i);
+ SELECT bt_index_check('idx',true);
+ SELECT pg_advisory_unlock(42);
+ \endif
+ ),
+ '004_pgbench_concurrent_ric' => q(
+ SELECT pg_try_advisory_lock(42)::integer AS gotlock \gset
+ \if :gotlock
+ REINDEX INDEX CONCURRENTLY idx;
+ SELECT bt_index_check('idx',true);
+ SELECT pg_advisory_unlock(42);
+ \endif
+ )
+ });
+
+$node->stop;
+done_testing();
diff --git a/contrib/amcheck/t/005_pitr.pl b/contrib/amcheck/t/005_pitr.pl
new file mode 100644
index 0000000..c8c8cf0
--- /dev/null
+++ b/contrib/amcheck/t/005_pitr.pl
@@ -0,0 +1,83 @@
+# Copyright (c) 2021-2023, PostgreSQL Global Development Group
+
+# Test integrity of intermediate states by PITR to those states
+use strict;
+use warnings;
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+# origin node: generate WAL records of interest.
+my $origin = PostgreSQL::Test::Cluster->new('origin');
+$origin->init(has_archiving => 1, allows_streaming => 1);
+$origin->append_conf('postgresql.conf', 'autovacuum = off');
+$origin->start;
+$origin->backup('my_backup');
+# Create a table with each of 6 PK values spanning 1/4 of a block. Delete the
+# first four, so one index leaf is eligible for deletion. Make a replication
+# slot just so pg_walinspect will always have access to later WAL.
+my $setup = <<EOSQL;
+BEGIN;
+CREATE EXTENSION amcheck;
+CREATE EXTENSION pg_walinspect;
+CREATE TABLE not_leftmost (c text);
+ALTER TABLE not_leftmost ALTER c SET STORAGE PLAIN;
+INSERT INTO not_leftmost
+ SELECT repeat(n::text, database_block_size / 4)
+ FROM generate_series(1,6) t(n), pg_control_init();
+ALTER TABLE not_leftmost ADD CONSTRAINT not_leftmost_pk PRIMARY KEY (c);
+DELETE FROM not_leftmost WHERE c ~ '^[1-4]';
+SELECT pg_create_physical_replication_slot('for_walinspect', true, false);
+COMMIT;
+EOSQL
+$origin->safe_psql('postgres', $setup);
+my $before_vacuum_lsn =
+ $origin->safe_psql('postgres', "SELECT pg_current_wal_lsn()");
+# VACUUM to delete the aforementioned leaf page. Force an XLogFlush() by
+# dropping a permanent table. That way, the XLogReader infrastructure can
+# always see VACUUM's records, even under synchronous_commit=off. Finally,
+# find the LSN of that VACUUM's last UNLINK_PAGE record.
+my $vacuum = <<EOSQL;
+SET synchronous_commit = off;
+VACUUM (VERBOSE, INDEX_CLEANUP ON) not_leftmost;
+CREATE TABLE XLogFlush ();
+DROP TABLE XLogFlush;
+SELECT max(start_lsn)
+ FROM pg_get_wal_records_info('$before_vacuum_lsn', pg_current_wal_flush_lsn())
+ WHERE resource_manager = 'Btree' AND record_type = 'UNLINK_PAGE';
+EOSQL
+my $unlink_lsn = $origin->safe_psql('postgres', $vacuum);
+$origin->stop;
+die "did not find UNLINK_PAGE record" unless $unlink_lsn;
+
+# replica node: amcheck at notable points in the WAL stream
+my $replica = PostgreSQL::Test::Cluster->new('replica');
+$replica->init_from_backup($origin, 'my_backup', has_restoring => 1);
+$replica->append_conf('postgresql.conf',
+ "recovery_target_lsn = '$unlink_lsn'");
+$replica->append_conf('postgresql.conf', 'recovery_target_inclusive = off');
+$replica->append_conf('postgresql.conf', 'recovery_target_action = promote');
+$replica->start;
+$replica->poll_query_until('postgres', "SELECT pg_is_in_recovery() = 'f';")
+ or die "Timed out while waiting for PITR promotion";
+# recovery done; run amcheck
+my $debug = "SET client_min_messages = 'debug1'";
+my ($rc, $stderr);
+$rc = $replica->psql(
+ 'postgres',
+ "$debug; SELECT bt_index_parent_check('not_leftmost_pk', true)",
+ stderr => \$stderr);
+print STDERR $stderr, "\n";
+is($rc, 0, "bt_index_parent_check passes");
+like(
+ $stderr,
+ qr/interrupted page deletion detected/,
+ "bt_index_parent_check: interrupted page deletion detected");
+$rc = $replica->psql(
+ 'postgres',
+ "$debug; SELECT bt_index_check('not_leftmost_pk', true)",
+ stderr => \$stderr);
+print STDERR $stderr, "\n";
+is($rc, 0, "bt_index_check passes");
+
+done_testing();
diff --git a/contrib/amcheck/verify_heapam.c b/contrib/amcheck/verify_heapam.c
new file mode 100644
index 0000000..4e3e87a
--- /dev/null
+++ b/contrib/amcheck/verify_heapam.c
@@ -0,0 +1,1782 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_heapam.c
+ * Functions to check postgresql heap relations for corruption
+ *
+ * Copyright (c) 2016-2022, PostgreSQL Global Development Group
+ *
+ * contrib/amcheck/verify_heapam.c
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/multixact.h"
+#include "access/toast_internals.h"
+#include "access/visibilitymap.h"
+#include "catalog/pg_am.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "storage/bufmgr.h"
+#include "storage/procarray.h"
+#include "utils/builtins.h"
+#include "utils/fmgroids.h"
+
+PG_FUNCTION_INFO_V1(verify_heapam);
+
+/* The number of columns in tuples returned by verify_heapam */
+#define HEAPCHECK_RELATION_COLS 4
+
+/* The largest valid toast va_rawsize */
+#define VARLENA_SIZE_LIMIT 0x3FFFFFFF
+
+/*
+ * Despite the name, we use this for reporting problems with both XIDs and
+ * MXIDs.
+ */
+typedef enum XidBoundsViolation
+{
+ XID_INVALID,
+ XID_IN_FUTURE,
+ XID_PRECEDES_CLUSTERMIN,
+ XID_PRECEDES_RELMIN,
+ XID_BOUNDS_OK
+} XidBoundsViolation;
+
+typedef enum XidCommitStatus
+{
+ XID_COMMITTED,
+ XID_IS_CURRENT_XID,
+ XID_IN_PROGRESS,
+ XID_ABORTED
+} XidCommitStatus;
+
+typedef enum SkipPages
+{
+ SKIP_PAGES_ALL_FROZEN,
+ SKIP_PAGES_ALL_VISIBLE,
+ SKIP_PAGES_NONE
+} SkipPages;
+
+/*
+ * Struct holding information about a toasted attribute sufficient to both
+ * check the toasted attribute and, if found to be corrupt, to report where it
+ * was encountered in the main table.
+ */
+typedef struct ToastedAttribute
+{
+ struct varatt_external toast_pointer;
+ BlockNumber blkno; /* block in main table */
+ OffsetNumber offnum; /* offset in main table */
+ AttrNumber attnum; /* attribute in main table */
+} ToastedAttribute;
+
+/*
+ * Struct holding the running context information during
+ * a lifetime of a verify_heapam execution.
+ */
+typedef struct HeapCheckContext
+{
+ /*
+ * Cached copies of values from ShmemVariableCache and computed values
+ * from them.
+ */
+ FullTransactionId next_fxid; /* ShmemVariableCache->nextXid */
+ TransactionId next_xid; /* 32-bit version of next_fxid */
+ TransactionId oldest_xid; /* ShmemVariableCache->oldestXid */
+ FullTransactionId oldest_fxid; /* 64-bit version of oldest_xid, computed
+ * relative to next_fxid */
+ TransactionId safe_xmin; /* this XID and newer ones can't become
+ * all-visible while we're running */
+
+ /*
+ * Cached copy of value from MultiXactState
+ */
+ MultiXactId next_mxact; /* MultiXactState->nextMXact */
+ MultiXactId oldest_mxact; /* MultiXactState->oldestMultiXactId */
+
+ /*
+ * Cached copies of the most recently checked xid and its status.
+ */
+ TransactionId cached_xid;
+ XidCommitStatus cached_status;
+
+ /* Values concerning the heap relation being checked */
+ Relation rel;
+ TransactionId relfrozenxid;
+ FullTransactionId relfrozenfxid;
+ TransactionId relminmxid;
+ Relation toast_rel;
+ Relation *toast_indexes;
+ Relation valid_toast_index;
+ int num_toast_indexes;
+
+ /* Values for iterating over pages in the relation */
+ BlockNumber blkno;
+ BufferAccessStrategy bstrategy;
+ Buffer buffer;
+ Page page;
+
+ /* Values for iterating over tuples within a page */
+ OffsetNumber offnum;
+ ItemId itemid;
+ uint16 lp_len;
+ uint16 lp_off;
+ HeapTupleHeader tuphdr;
+ int natts;
+
+ /* Values for iterating over attributes within the tuple */
+ uint32 offset; /* offset in tuple data */
+ AttrNumber attnum;
+
+ /* True if tuple's xmax makes it eligible for pruning */
+ bool tuple_could_be_pruned;
+
+ /*
+ * List of ToastedAttribute structs for toasted attributes which are not
+ * eligible for pruning and should be checked
+ */
+ List *toasted_attributes;
+
+ /* Whether verify_heapam has yet encountered any corrupt tuples */
+ bool is_corrupt;
+
+ /* The descriptor and tuplestore for verify_heapam's result tuples */
+ TupleDesc tupdesc;
+ Tuplestorestate *tupstore;
+} HeapCheckContext;
+
+/* Internal implementation */
+static void check_tuple(HeapCheckContext *ctx);
+static void check_toast_tuple(HeapTuple toasttup, HeapCheckContext *ctx,
+ ToastedAttribute *ta, int32 *expected_chunk_seq,
+ uint32 extsize);
+
+static bool check_tuple_attribute(HeapCheckContext *ctx);
+static void check_toasted_attribute(HeapCheckContext *ctx,
+ ToastedAttribute *ta);
+
+static bool check_tuple_header(HeapCheckContext *ctx);
+static bool check_tuple_visibility(HeapCheckContext *ctx);
+
+static void report_corruption(HeapCheckContext *ctx, char *msg);
+static void report_toast_corruption(HeapCheckContext *ctx,
+ ToastedAttribute *ta, char *msg);
+static FullTransactionId FullTransactionIdFromXidAndCtx(TransactionId xid,
+ const HeapCheckContext *ctx);
+static void update_cached_xid_range(HeapCheckContext *ctx);
+static void update_cached_mxid_range(HeapCheckContext *ctx);
+static XidBoundsViolation check_mxid_in_range(MultiXactId mxid,
+ HeapCheckContext *ctx);
+static XidBoundsViolation check_mxid_valid_in_rel(MultiXactId mxid,
+ HeapCheckContext *ctx);
+static XidBoundsViolation get_xid_status(TransactionId xid,
+ HeapCheckContext *ctx,
+ XidCommitStatus *status);
+
+/*
+ * Scan and report corruption in heap pages, optionally reconciling toasted
+ * attributes with entries in the associated toast table. Intended to be
+ * called from SQL with the following parameters:
+ *
+ * relation:
+ * The Oid of the heap relation to be checked.
+ *
+ * on_error_stop:
+ * Whether to stop at the end of the first page for which errors are
+ * detected. Note that multiple rows may be returned.
+ *
+ * check_toast:
+ * Whether to check each toasted attribute against the toast table to
+ * verify that it can be found there.
+ *
+ * skip:
+ * What kinds of pages in the heap relation should be skipped. Valid
+ * options are "all-visible", "all-frozen", and "none".
+ *
+ * Returns to the SQL caller a set of tuples, each containing the location
+ * and a description of a corruption found in the heap.
+ *
+ * This code goes to some trouble to avoid crashing the server even if the
+ * table pages are badly corrupted, but it's probably not perfect. If
+ * check_toast is true, we'll use regular index lookups to try to fetch TOAST
+ * tuples, which can certainly cause crashes if the right kind of corruption
+ * exists in the toast table or index. No matter what parameters you pass,
+ * we can't protect against crashes that might occur trying to look up the
+ * commit status of transaction IDs (though we avoid trying to do such lookups
+ * for transaction IDs that can't legally appear in the table).
+ */
+Datum
+verify_heapam(PG_FUNCTION_ARGS)
+{
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+ HeapCheckContext ctx;
+ Buffer vmbuffer = InvalidBuffer;
+ Oid relid;
+ bool on_error_stop;
+ bool check_toast;
+ SkipPages skip_option = SKIP_PAGES_NONE;
+ BlockNumber first_block;
+ BlockNumber last_block;
+ BlockNumber nblocks;
+ const char *skip;
+
+ /* Check supplied arguments */
+ if (PG_ARGISNULL(0))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("relation cannot be null")));
+ relid = PG_GETARG_OID(0);
+
+ if (PG_ARGISNULL(1))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("on_error_stop cannot be null")));
+ on_error_stop = PG_GETARG_BOOL(1);
+
+ if (PG_ARGISNULL(2))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("check_toast cannot be null")));
+ check_toast = PG_GETARG_BOOL(2);
+
+ if (PG_ARGISNULL(3))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("skip cannot be null")));
+ skip = text_to_cstring(PG_GETARG_TEXT_PP(3));
+ if (pg_strcasecmp(skip, "all-visible") == 0)
+ skip_option = SKIP_PAGES_ALL_VISIBLE;
+ else if (pg_strcasecmp(skip, "all-frozen") == 0)
+ skip_option = SKIP_PAGES_ALL_FROZEN;
+ else if (pg_strcasecmp(skip, "none") == 0)
+ skip_option = SKIP_PAGES_NONE;
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("invalid skip option"),
+ errhint("Valid skip options are \"all-visible\", \"all-frozen\", and \"none\".")));
+
+ memset(&ctx, 0, sizeof(HeapCheckContext));
+ ctx.cached_xid = InvalidTransactionId;
+ ctx.toasted_attributes = NIL;
+
+ /*
+ * Any xmin newer than the xmin of our snapshot can't become all-visible
+ * while we're running.
+ */
+ ctx.safe_xmin = GetTransactionSnapshot()->xmin;
+
+ /*
+ * If we report corruption when not examining some individual attribute,
+ * we need attnum to be reported as NULL. Set that up before any
+ * corruption reporting might happen.
+ */
+ ctx.attnum = -1;
+
+ /* Construct the tuplestore and tuple descriptor */
+ InitMaterializedSRF(fcinfo, 0);
+ ctx.tupdesc = rsinfo->setDesc;
+ ctx.tupstore = rsinfo->setResult;
+
+ /* Open relation, check relkind and access method */
+ ctx.rel = relation_open(relid, AccessShareLock);
+
+ /*
+ * Check that a relation's relkind and access method are both supported.
+ */
+ if (!RELKIND_HAS_TABLE_AM(ctx.rel->rd_rel->relkind) &&
+ ctx.rel->rd_rel->relkind != RELKIND_SEQUENCE)
+ ereport(ERROR,
+ (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+ errmsg("cannot check relation \"%s\"",
+ RelationGetRelationName(ctx.rel)),
+ errdetail_relkind_not_supported(ctx.rel->rd_rel->relkind)));
+
+ /*
+ * Sequences always use heap AM, but they don't show that in the catalogs.
+ * Other relkinds might be using a different AM, so check.
+ */
+ if (ctx.rel->rd_rel->relkind != RELKIND_SEQUENCE &&
+ ctx.rel->rd_rel->relam != HEAP_TABLE_AM_OID)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("only heap AM is supported")));
+
+ /*
+ * Early exit for unlogged relations during recovery. These will have no
+ * relation fork, so there won't be anything to check. We behave as if
+ * the relation is empty.
+ */
+ if (ctx.rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED &&
+ RecoveryInProgress())
+ {
+ ereport(DEBUG1,
+ (errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+ errmsg("cannot verify unlogged relation \"%s\" during recovery, skipping",
+ RelationGetRelationName(ctx.rel))));
+ relation_close(ctx.rel, AccessShareLock);
+ PG_RETURN_NULL();
+ }
+
+ /* Early exit if the relation is empty */
+ nblocks = RelationGetNumberOfBlocks(ctx.rel);
+ if (!nblocks)
+ {
+ relation_close(ctx.rel, AccessShareLock);
+ PG_RETURN_NULL();
+ }
+
+ ctx.bstrategy = GetAccessStrategy(BAS_BULKREAD);
+ ctx.buffer = InvalidBuffer;
+ ctx.page = NULL;
+
+ /* Validate block numbers, or handle nulls. */
+ if (PG_ARGISNULL(4))
+ first_block = 0;
+ else
+ {
+ int64 fb = PG_GETARG_INT64(4);
+
+ if (fb < 0 || fb >= nblocks)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("starting block number must be between 0 and %u",
+ nblocks - 1)));
+ first_block = (BlockNumber) fb;
+ }
+ if (PG_ARGISNULL(5))
+ last_block = nblocks - 1;
+ else
+ {
+ int64 lb = PG_GETARG_INT64(5);
+
+ if (lb < 0 || lb >= nblocks)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("ending block number must be between 0 and %u",
+ nblocks - 1)));
+ last_block = (BlockNumber) lb;
+ }
+
+ /* Optionally open the toast relation, if any. */
+ if (ctx.rel->rd_rel->reltoastrelid && check_toast)
+ {
+ int offset;
+
+ /* Main relation has associated toast relation */
+ ctx.toast_rel = table_open(ctx.rel->rd_rel->reltoastrelid,
+ AccessShareLock);
+ offset = toast_open_indexes(ctx.toast_rel,
+ AccessShareLock,
+ &(ctx.toast_indexes),
+ &(ctx.num_toast_indexes));
+ ctx.valid_toast_index = ctx.toast_indexes[offset];
+ }
+ else
+ {
+ /*
+ * Main relation has no associated toast relation, or we're
+ * intentionally skipping it.
+ */
+ ctx.toast_rel = NULL;
+ ctx.toast_indexes = NULL;
+ ctx.num_toast_indexes = 0;
+ }
+
+ update_cached_xid_range(&ctx);
+ update_cached_mxid_range(&ctx);
+ ctx.relfrozenxid = ctx.rel->rd_rel->relfrozenxid;
+ ctx.relfrozenfxid = FullTransactionIdFromXidAndCtx(ctx.relfrozenxid, &ctx);
+ ctx.relminmxid = ctx.rel->rd_rel->relminmxid;
+
+ if (TransactionIdIsNormal(ctx.relfrozenxid))
+ ctx.oldest_xid = ctx.relfrozenxid;
+
+ for (ctx.blkno = first_block; ctx.blkno <= last_block; ctx.blkno++)
+ {
+ OffsetNumber maxoff;
+
+ CHECK_FOR_INTERRUPTS();
+
+ /* Optionally skip over all-frozen or all-visible blocks */
+ if (skip_option != SKIP_PAGES_NONE)
+ {
+ int32 mapbits;
+
+ mapbits = (int32) visibilitymap_get_status(ctx.rel, ctx.blkno,
+ &vmbuffer);
+ if (skip_option == SKIP_PAGES_ALL_FROZEN)
+ {
+ if ((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0)
+ continue;
+ }
+
+ if (skip_option == SKIP_PAGES_ALL_VISIBLE)
+ {
+ if ((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0)
+ continue;
+ }
+ }
+
+ /* Read and lock the next page. */
+ ctx.buffer = ReadBufferExtended(ctx.rel, MAIN_FORKNUM, ctx.blkno,
+ RBM_NORMAL, ctx.bstrategy);
+ LockBuffer(ctx.buffer, BUFFER_LOCK_SHARE);
+ ctx.page = BufferGetPage(ctx.buffer);
+
+ /* Perform tuple checks */
+ maxoff = PageGetMaxOffsetNumber(ctx.page);
+ for (ctx.offnum = FirstOffsetNumber; ctx.offnum <= maxoff;
+ ctx.offnum = OffsetNumberNext(ctx.offnum))
+ {
+ ctx.itemid = PageGetItemId(ctx.page, ctx.offnum);
+
+ /* Skip over unused/dead line pointers */
+ if (!ItemIdIsUsed(ctx.itemid) || ItemIdIsDead(ctx.itemid))
+ continue;
+
+ /*
+ * If this line pointer has been redirected, check that it
+ * redirects to a valid offset within the line pointer array
+ */
+ if (ItemIdIsRedirected(ctx.itemid))
+ {
+ OffsetNumber rdoffnum = ItemIdGetRedirect(ctx.itemid);
+ ItemId rditem;
+
+ if (rdoffnum < FirstOffsetNumber)
+ {
+ report_corruption(&ctx,
+ psprintf("line pointer redirection to item at offset %u precedes minimum offset %u",
+ (unsigned) rdoffnum,
+ (unsigned) FirstOffsetNumber));
+ continue;
+ }
+ if (rdoffnum > maxoff)
+ {
+ report_corruption(&ctx,
+ psprintf("line pointer redirection to item at offset %u exceeds maximum offset %u",
+ (unsigned) rdoffnum,
+ (unsigned) maxoff));
+ continue;
+ }
+ rditem = PageGetItemId(ctx.page, rdoffnum);
+ if (!ItemIdIsUsed(rditem))
+ report_corruption(&ctx,
+ psprintf("line pointer redirection to unused item at offset %u",
+ (unsigned) rdoffnum));
+ continue;
+ }
+
+ /* Sanity-check the line pointer's offset and length values */
+ ctx.lp_len = ItemIdGetLength(ctx.itemid);
+ ctx.lp_off = ItemIdGetOffset(ctx.itemid);
+
+ if (ctx.lp_off != MAXALIGN(ctx.lp_off))
+ {
+ report_corruption(&ctx,
+ psprintf("line pointer to page offset %u is not maximally aligned",
+ ctx.lp_off));
+ continue;
+ }
+ if (ctx.lp_len < MAXALIGN(SizeofHeapTupleHeader))
+ {
+ report_corruption(&ctx,
+ psprintf("line pointer length %u is less than the minimum tuple header size %u",
+ ctx.lp_len,
+ (unsigned) MAXALIGN(SizeofHeapTupleHeader)));
+ continue;
+ }
+ if (ctx.lp_off + ctx.lp_len > BLCKSZ)
+ {
+ report_corruption(&ctx,
+ psprintf("line pointer to page offset %u with length %u ends beyond maximum page offset %u",
+ ctx.lp_off,
+ ctx.lp_len,
+ (unsigned) BLCKSZ));
+ continue;
+ }
+
+ /* It should be safe to examine the tuple's header, at least */
+ ctx.tuphdr = (HeapTupleHeader) PageGetItem(ctx.page, ctx.itemid);
+ ctx.natts = HeapTupleHeaderGetNatts(ctx.tuphdr);
+
+ /* Ok, ready to check this next tuple */
+ check_tuple(&ctx);
+ }
+
+ /* clean up */
+ UnlockReleaseBuffer(ctx.buffer);
+
+ /*
+ * Check any toast pointers from the page whose lock we just released
+ */
+ if (ctx.toasted_attributes != NIL)
+ {
+ ListCell *cell;
+
+ foreach(cell, ctx.toasted_attributes)
+ check_toasted_attribute(&ctx, lfirst(cell));
+ list_free_deep(ctx.toasted_attributes);
+ ctx.toasted_attributes = NIL;
+ }
+
+ if (on_error_stop && ctx.is_corrupt)
+ break;
+ }
+
+ if (vmbuffer != InvalidBuffer)
+ ReleaseBuffer(vmbuffer);
+
+ /* Close the associated toast table and indexes, if any. */
+ if (ctx.toast_indexes)
+ toast_close_indexes(ctx.toast_indexes, ctx.num_toast_indexes,
+ AccessShareLock);
+ if (ctx.toast_rel)
+ table_close(ctx.toast_rel, AccessShareLock);
+
+ /* Close the main relation */
+ relation_close(ctx.rel, AccessShareLock);
+
+ PG_RETURN_NULL();
+}
+
+/*
+ * Shared internal implementation for report_corruption and
+ * report_toast_corruption.
+ */
+static void
+report_corruption_internal(Tuplestorestate *tupstore, TupleDesc tupdesc,
+ BlockNumber blkno, OffsetNumber offnum,
+ AttrNumber attnum, char *msg)
+{
+ Datum values[HEAPCHECK_RELATION_COLS];
+ bool nulls[HEAPCHECK_RELATION_COLS];
+ HeapTuple tuple;
+
+ MemSet(values, 0, sizeof(values));
+ MemSet(nulls, 0, sizeof(nulls));
+ values[0] = Int64GetDatum(blkno);
+ values[1] = Int32GetDatum(offnum);
+ values[2] = Int32GetDatum(attnum);
+ nulls[2] = (attnum < 0);
+ values[3] = CStringGetTextDatum(msg);
+
+ /*
+ * In principle, there is nothing to prevent a scan over a large, highly
+ * corrupted table from using work_mem worth of memory building up the
+ * tuplestore. That's ok, but if we also leak the msg argument memory
+ * until the end of the query, we could exceed work_mem by more than a
+ * trivial amount. Therefore, free the msg argument each time we are
+ * called rather than waiting for our current memory context to be freed.
+ */
+ pfree(msg);
+
+ tuple = heap_form_tuple(tupdesc, values, nulls);
+ tuplestore_puttuple(tupstore, tuple);
+}
+
+/*
+ * Record a single corruption found in the main table. The values in ctx should
+ * indicate the location of the corruption, and the msg argument should contain
+ * a human-readable description of the corruption.
+ *
+ * The msg argument is pfree'd by this function.
+ */
+static void
+report_corruption(HeapCheckContext *ctx, char *msg)
+{
+ report_corruption_internal(ctx->tupstore, ctx->tupdesc, ctx->blkno,
+ ctx->offnum, ctx->attnum, msg);
+ ctx->is_corrupt = true;
+}
+
+/*
+ * Record corruption found in the toast table. The values in ta should
+ * indicate the location in the main table where the toast pointer was
+ * encountered, and the msg argument should contain a human-readable
+ * description of the toast table corruption.
+ *
+ * As above, the msg argument is pfree'd by this function.
+ */
+static void
+report_toast_corruption(HeapCheckContext *ctx, ToastedAttribute *ta,
+ char *msg)
+{
+ report_corruption_internal(ctx->tupstore, ctx->tupdesc, ta->blkno,
+ ta->offnum, ta->attnum, msg);
+ ctx->is_corrupt = true;
+}
+
+/*
+ * Check for tuple header corruption.
+ *
+ * Some kinds of corruption make it unsafe to check the tuple attributes, for
+ * example when the line pointer refers to a range of bytes outside the page.
+ * In such cases, we return false (not checkable) after recording appropriate
+ * corruption messages.
+ *
+ * Some other kinds of tuple header corruption confuse the question of where
+ * the tuple attributes begin, or how long the nulls bitmap is, etc., making it
+ * unreasonable to attempt to check attributes, even if all candidate answers
+ * to those questions would not result in reading past the end of the line
+ * pointer or page. In such cases, like above, we record corruption messages
+ * about the header and then return false.
+ *
+ * Other kinds of tuple header corruption do not bear on the question of
+ * whether the tuple attributes can be checked, so we record corruption
+ * messages for them but we do not return false merely because we detected
+ * them.
+ *
+ * Returns whether the tuple is sufficiently sensible to undergo visibility and
+ * attribute checks.
+ */
+static bool
+check_tuple_header(HeapCheckContext *ctx)
+{
+ HeapTupleHeader tuphdr = ctx->tuphdr;
+ uint16 infomask = tuphdr->t_infomask;
+ bool result = true;
+ unsigned expected_hoff;
+
+ if (ctx->tuphdr->t_hoff > ctx->lp_len)
+ {
+ report_corruption(ctx,
+ psprintf("data begins at offset %u beyond the tuple length %u",
+ ctx->tuphdr->t_hoff, ctx->lp_len));
+ result = false;
+ }
+
+ if ((ctx->tuphdr->t_infomask & HEAP_XMAX_COMMITTED) &&
+ (ctx->tuphdr->t_infomask & HEAP_XMAX_IS_MULTI))
+ {
+ report_corruption(ctx,
+ pstrdup("multixact should not be marked committed"));
+
+ /*
+ * This condition is clearly wrong, but it's not enough to justify
+ * skipping further checks, because we don't rely on this to determine
+ * whether the tuple is visible or to interpret other relevant header
+ * fields.
+ */
+ }
+
+ if (infomask & HEAP_HASNULL)
+ expected_hoff = MAXALIGN(SizeofHeapTupleHeader + BITMAPLEN(ctx->natts));
+ else
+ expected_hoff = MAXALIGN(SizeofHeapTupleHeader);
+ if (ctx->tuphdr->t_hoff != expected_hoff)
+ {
+ if ((infomask & HEAP_HASNULL) && ctx->natts == 1)
+ report_corruption(ctx,
+ psprintf("tuple data should begin at byte %u, but actually begins at byte %u (1 attribute, has nulls)",
+ expected_hoff, ctx->tuphdr->t_hoff));
+ else if ((infomask & HEAP_HASNULL))
+ report_corruption(ctx,
+ psprintf("tuple data should begin at byte %u, but actually begins at byte %u (%u attributes, has nulls)",
+ expected_hoff, ctx->tuphdr->t_hoff, ctx->natts));
+ else if (ctx->natts == 1)
+ report_corruption(ctx,
+ psprintf("tuple data should begin at byte %u, but actually begins at byte %u (1 attribute, no nulls)",
+ expected_hoff, ctx->tuphdr->t_hoff));
+ else
+ report_corruption(ctx,
+ psprintf("tuple data should begin at byte %u, but actually begins at byte %u (%u attributes, no nulls)",
+ expected_hoff, ctx->tuphdr->t_hoff, ctx->natts));
+ result = false;
+ }
+
+ return result;
+}
+
+/*
+ * Checks tuple visibility so we know which further checks are safe to
+ * perform.
+ *
+ * If a tuple could have been inserted by a transaction that also added a
+ * column to the table, but which ultimately did not commit, or which has not
+ * yet committed, then the table's current TupleDesc might differ from the one
+ * used to construct this tuple, so we must not check it.
+ *
+ * As a special case, if our own transaction inserted the tuple, even if we
+ * added a column to the table, our TupleDesc should match. We could check the
+ * tuple, but choose not to do so.
+ *
+ * If a tuple has been updated or deleted, we can still read the old tuple for
+ * corruption checking purposes, as long as we are careful about concurrent
+ * vacuums. The main table tuple itself cannot be vacuumed away because we
+ * hold a buffer lock on the page, but if the deleting transaction is older
+ * than our transaction snapshot's xmin, then vacuum could remove the toast at
+ * any time, so we must not try to follow TOAST pointers.
+ *
+ * If xmin or xmax values are older than can be checked against clog, or appear
+ * to be in the future (possibly due to wrap-around), then we cannot make a
+ * determination about the visibility of the tuple, so we skip further checks.
+ *
+ * Returns true if the tuple itself should be checked, false otherwise. Sets
+ * ctx->tuple_could_be_pruned if the tuple -- and thus also any associated
+ * TOAST tuples -- are eligible for pruning.
+ */
+static bool
+check_tuple_visibility(HeapCheckContext *ctx)
+{
+ TransactionId xmin;
+ TransactionId xvac;
+ TransactionId xmax;
+ XidCommitStatus xmin_status;
+ XidCommitStatus xvac_status;
+ XidCommitStatus xmax_status;
+ HeapTupleHeader tuphdr = ctx->tuphdr;
+
+ ctx->tuple_could_be_pruned = true; /* have not yet proven otherwise */
+
+ /* If xmin is normal, it should be within valid range */
+ xmin = HeapTupleHeaderGetXmin(tuphdr);
+ switch (get_xid_status(xmin, ctx, &xmin_status))
+ {
+ case XID_INVALID:
+ /* Could be the result of a speculative insertion that aborted. */
+ return false;
+ case XID_BOUNDS_OK:
+ break;
+ case XID_IN_FUTURE:
+ report_corruption(ctx,
+ psprintf("xmin %u equals or exceeds next valid transaction ID %u:%u",
+ xmin,
+ EpochFromFullTransactionId(ctx->next_fxid),
+ XidFromFullTransactionId(ctx->next_fxid)));
+ return false;
+ case XID_PRECEDES_CLUSTERMIN:
+ report_corruption(ctx,
+ psprintf("xmin %u precedes oldest valid transaction ID %u:%u",
+ xmin,
+ EpochFromFullTransactionId(ctx->oldest_fxid),
+ XidFromFullTransactionId(ctx->oldest_fxid)));
+ return false;
+ case XID_PRECEDES_RELMIN:
+ report_corruption(ctx,
+ psprintf("xmin %u precedes relation freeze threshold %u:%u",
+ xmin,
+ EpochFromFullTransactionId(ctx->relfrozenfxid),
+ XidFromFullTransactionId(ctx->relfrozenfxid)));
+ return false;
+ }
+
+ /*
+ * Has inserting transaction committed?
+ */
+ if (!HeapTupleHeaderXminCommitted(tuphdr))
+ {
+ if (HeapTupleHeaderXminInvalid(tuphdr))
+ return false; /* inserter aborted, don't check */
+ /* Used by pre-9.0 binary upgrades */
+ else if (tuphdr->t_infomask & HEAP_MOVED_OFF)
+ {
+ xvac = HeapTupleHeaderGetXvac(tuphdr);
+
+ switch (get_xid_status(xvac, ctx, &xvac_status))
+ {
+ case XID_INVALID:
+ report_corruption(ctx,
+ pstrdup("old-style VACUUM FULL transaction ID for moved off tuple is invalid"));
+ return false;
+ case XID_IN_FUTURE:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple equals or exceeds next valid transaction ID %u:%u",
+ xvac,
+ EpochFromFullTransactionId(ctx->next_fxid),
+ XidFromFullTransactionId(ctx->next_fxid)));
+ return false;
+ case XID_PRECEDES_RELMIN:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple precedes relation freeze threshold %u:%u",
+ xvac,
+ EpochFromFullTransactionId(ctx->relfrozenfxid),
+ XidFromFullTransactionId(ctx->relfrozenfxid)));
+ return false;
+ case XID_PRECEDES_CLUSTERMIN:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple precedes oldest valid transaction ID %u:%u",
+ xvac,
+ EpochFromFullTransactionId(ctx->oldest_fxid),
+ XidFromFullTransactionId(ctx->oldest_fxid)));
+ return false;
+ case XID_BOUNDS_OK:
+ break;
+ }
+
+ switch (xvac_status)
+ {
+ case XID_IS_CURRENT_XID:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple matches our current transaction ID",
+ xvac));
+ return false;
+ case XID_IN_PROGRESS:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple appears to be in progress",
+ xvac));
+ return false;
+
+ case XID_COMMITTED:
+
+ /*
+ * The tuple is dead, because the xvac transaction moved
+ * it off and committed. It's checkable, but also
+ * prunable.
+ */
+ return true;
+
+ case XID_ABORTED:
+
+ /*
+ * The original xmin must have committed, because the xvac
+ * transaction tried to move it later. Since xvac is
+ * aborted, whether it's still alive now depends on the
+ * status of xmax.
+ */
+ break;
+ }
+ }
+ /* Used by pre-9.0 binary upgrades */
+ else if (tuphdr->t_infomask & HEAP_MOVED_IN)
+ {
+ xvac = HeapTupleHeaderGetXvac(tuphdr);
+
+ switch (get_xid_status(xvac, ctx, &xvac_status))
+ {
+ case XID_INVALID:
+ report_corruption(ctx,
+ pstrdup("old-style VACUUM FULL transaction ID for moved in tuple is invalid"));
+ return false;
+ case XID_IN_FUTURE:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple equals or exceeds next valid transaction ID %u:%u",
+ xvac,
+ EpochFromFullTransactionId(ctx->next_fxid),
+ XidFromFullTransactionId(ctx->next_fxid)));
+ return false;
+ case XID_PRECEDES_RELMIN:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple precedes relation freeze threshold %u:%u",
+ xvac,
+ EpochFromFullTransactionId(ctx->relfrozenfxid),
+ XidFromFullTransactionId(ctx->relfrozenfxid)));
+ return false;
+ case XID_PRECEDES_CLUSTERMIN:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple precedes oldest valid transaction ID %u:%u",
+ xvac,
+ EpochFromFullTransactionId(ctx->oldest_fxid),
+ XidFromFullTransactionId(ctx->oldest_fxid)));
+ return false;
+ case XID_BOUNDS_OK:
+ break;
+ }
+
+ switch (xvac_status)
+ {
+ case XID_IS_CURRENT_XID:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple matches our current transaction ID",
+ xvac));
+ return false;
+ case XID_IN_PROGRESS:
+ report_corruption(ctx,
+ psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple appears to be in progress",
+ xvac));
+ return false;
+
+ case XID_COMMITTED:
+
+ /*
+ * The original xmin must have committed, because the xvac
+ * transaction moved it later. Whether it's still alive
+ * now depends on the status of xmax.
+ */
+ break;
+
+ case XID_ABORTED:
+
+ /*
+ * The tuple is dead, because the xvac transaction moved
+ * it off and committed. It's checkable, but also
+ * prunable.
+ */
+ return true;
+ }
+ }
+ else if (xmin_status != XID_COMMITTED)
+ {
+ /*
+ * Inserting transaction is not in progress, and not committed, so
+ * it might have changed the TupleDesc in ways we don't know
+ * about. Thus, don't try to check the tuple structure.
+ *
+ * If xmin_status happens to be XID_IS_CURRENT_XID, then in theory
+ * any such DDL changes ought to be visible to us, so perhaps we
+ * could check anyway in that case. But, for now, let's be
+ * conservative and treat this like any other uncommitted insert.
+ */
+ return false;
+ }
+ }
+
+ /*
+ * Okay, the inserter committed, so it was good at some point. Now what
+ * about the deleting transaction?
+ */
+
+ if (tuphdr->t_infomask & HEAP_XMAX_IS_MULTI)
+ {
+ /*
+ * xmax is a multixact, so sanity-check the MXID. Note that we do this
+ * prior to checking for HEAP_XMAX_INVALID or
+ * HEAP_XMAX_IS_LOCKED_ONLY. This might therefore complain about
+ * things that wouldn't actually be a problem during a normal scan,
+ * but eventually we're going to have to freeze, and that process will
+ * ignore hint bits.
+ *
+ * Even if the MXID is out of range, we still know that the original
+ * insert committed, so we can check the tuple itself. However, we
+ * can't rule out the possibility that this tuple is dead, so don't
+ * clear ctx->tuple_could_be_pruned. Possibly we should go ahead and
+ * clear that flag anyway if HEAP_XMAX_INVALID is set or if
+ * HEAP_XMAX_IS_LOCKED_ONLY is true, but for now we err on the side of
+ * avoiding possibly-bogus complaints about missing TOAST entries.
+ */
+ xmax = HeapTupleHeaderGetRawXmax(tuphdr);
+ switch (check_mxid_valid_in_rel(xmax, ctx))
+ {
+ case XID_INVALID:
+ report_corruption(ctx,
+ pstrdup("multitransaction ID is invalid"));
+ return true;
+ case XID_PRECEDES_RELMIN:
+ report_corruption(ctx,
+ psprintf("multitransaction ID %u precedes relation minimum multitransaction ID threshold %u",
+ xmax, ctx->relminmxid));
+ return true;
+ case XID_PRECEDES_CLUSTERMIN:
+ report_corruption(ctx,
+ psprintf("multitransaction ID %u precedes oldest valid multitransaction ID threshold %u",
+ xmax, ctx->oldest_mxact));
+ return true;
+ case XID_IN_FUTURE:
+ report_corruption(ctx,
+ psprintf("multitransaction ID %u equals or exceeds next valid multitransaction ID %u",
+ xmax,
+ ctx->next_mxact));
+ return true;
+ case XID_BOUNDS_OK:
+ break;
+ }
+ }
+
+ if (tuphdr->t_infomask & HEAP_XMAX_INVALID)
+ {
+ /*
+ * This tuple is live. A concurrently running transaction could
+ * delete it before we get around to checking the toast, but any such
+ * running transaction is surely not less than our safe_xmin, so the
+ * toast cannot be vacuumed out from under us.
+ */
+ ctx->tuple_could_be_pruned = false;
+ return true;
+ }
+
+ if (HEAP_XMAX_IS_LOCKED_ONLY(tuphdr->t_infomask))
+ {
+ /*
+ * "Deleting" xact really only locked it, so the tuple is live in any
+ * case. As above, a concurrently running transaction could delete
+ * it, but it cannot be vacuumed out from under us.
+ */
+ ctx->tuple_could_be_pruned = false;
+ return true;
+ }
+
+ if (tuphdr->t_infomask & HEAP_XMAX_IS_MULTI)
+ {
+ /*
+ * We already checked above that this multixact is within limits for
+ * this table. Now check the update xid from this multixact.
+ */
+ xmax = HeapTupleGetUpdateXid(tuphdr);
+ switch (get_xid_status(xmax, ctx, &xmax_status))
+ {
+ case XID_INVALID:
+ /* not LOCKED_ONLY, so it has to have an xmax */
+ report_corruption(ctx,
+ pstrdup("update xid is invalid"));
+ return true;
+ case XID_IN_FUTURE:
+ report_corruption(ctx,
+ psprintf("update xid %u equals or exceeds next valid transaction ID %u:%u",
+ xmax,
+ EpochFromFullTransactionId(ctx->next_fxid),
+ XidFromFullTransactionId(ctx->next_fxid)));
+ return true;
+ case XID_PRECEDES_RELMIN:
+ report_corruption(ctx,
+ psprintf("update xid %u precedes relation freeze threshold %u:%u",
+ xmax,
+ EpochFromFullTransactionId(ctx->relfrozenfxid),
+ XidFromFullTransactionId(ctx->relfrozenfxid)));
+ return true;
+ case XID_PRECEDES_CLUSTERMIN:
+ report_corruption(ctx,
+ psprintf("update xid %u precedes oldest valid transaction ID %u:%u",
+ xmax,
+ EpochFromFullTransactionId(ctx->oldest_fxid),
+ XidFromFullTransactionId(ctx->oldest_fxid)));
+ return true;
+ case XID_BOUNDS_OK:
+ break;
+ }
+
+ switch (xmax_status)
+ {
+ case XID_IS_CURRENT_XID:
+ case XID_IN_PROGRESS:
+
+ /*
+ * The delete is in progress, so it cannot be visible to our
+ * snapshot.
+ */
+ ctx->tuple_could_be_pruned = false;
+ break;
+ case XID_COMMITTED:
+
+ /*
+ * The delete committed. Whether the toast can be vacuumed
+ * away depends on how old the deleting transaction is.
+ */
+ ctx->tuple_could_be_pruned = TransactionIdPrecedes(xmax,
+ ctx->safe_xmin);
+ break;
+ case XID_ABORTED:
+
+ /*
+ * The delete aborted or crashed. The tuple is still live.
+ */
+ ctx->tuple_could_be_pruned = false;
+ break;
+ }
+
+ /* Tuple itself is checkable even if it's dead. */
+ return true;
+ }
+
+ /* xmax is an XID, not a MXID. Sanity check it. */
+ xmax = HeapTupleHeaderGetRawXmax(tuphdr);
+ switch (get_xid_status(xmax, ctx, &xmax_status))
+ {
+ case XID_INVALID:
+ ctx->tuple_could_be_pruned = false;
+ return true;
+ case XID_IN_FUTURE:
+ report_corruption(ctx,
+ psprintf("xmax %u equals or exceeds next valid transaction ID %u:%u",
+ xmax,
+ EpochFromFullTransactionId(ctx->next_fxid),
+ XidFromFullTransactionId(ctx->next_fxid)));
+ return false; /* corrupt */
+ case XID_PRECEDES_RELMIN:
+ report_corruption(ctx,
+ psprintf("xmax %u precedes relation freeze threshold %u:%u",
+ xmax,
+ EpochFromFullTransactionId(ctx->relfrozenfxid),
+ XidFromFullTransactionId(ctx->relfrozenfxid)));
+ return false; /* corrupt */
+ case XID_PRECEDES_CLUSTERMIN:
+ report_corruption(ctx,
+ psprintf("xmax %u precedes oldest valid transaction ID %u:%u",
+ xmax,
+ EpochFromFullTransactionId(ctx->oldest_fxid),
+ XidFromFullTransactionId(ctx->oldest_fxid)));
+ return false; /* corrupt */
+ case XID_BOUNDS_OK:
+ break;
+ }
+
+ /*
+ * Whether the toast can be vacuumed away depends on how old the deleting
+ * transaction is.
+ */
+ switch (xmax_status)
+ {
+ case XID_IS_CURRENT_XID:
+ case XID_IN_PROGRESS:
+
+ /*
+ * The delete is in progress, so it cannot be visible to our
+ * snapshot.
+ */
+ ctx->tuple_could_be_pruned = false;
+ break;
+
+ case XID_COMMITTED:
+
+ /*
+ * The delete committed. Whether the toast can be vacuumed away
+ * depends on how old the deleting transaction is.
+ */
+ ctx->tuple_could_be_pruned = TransactionIdPrecedes(xmax,
+ ctx->safe_xmin);
+ break;
+
+ case XID_ABORTED:
+
+ /*
+ * The delete aborted or crashed. The tuple is still live.
+ */
+ ctx->tuple_could_be_pruned = false;
+ break;
+ }
+
+ /* Tuple itself is checkable even if it's dead. */
+ return true;
+}
+
+
+/*
+ * Check the current toast tuple against the state tracked in ctx, recording
+ * any corruption found in ctx->tupstore.
+ *
+ * This is not equivalent to running verify_heapam on the toast table itself,
+ * and is not hardened against corruption of the toast table. Rather, when
+ * validating a toasted attribute in the main table, the sequence of toast
+ * tuples that store the toasted value are retrieved and checked in order, with
+ * each toast tuple being checked against where we are in the sequence, as well
+ * as each toast tuple having its varlena structure sanity checked.
+ *
+ * On entry, *expected_chunk_seq should be the chunk_seq value that we expect
+ * to find in toasttup. On exit, it will be updated to the value the next call
+ * to this function should expect to see.
+ */
+static void
+check_toast_tuple(HeapTuple toasttup, HeapCheckContext *ctx,
+ ToastedAttribute *ta, int32 *expected_chunk_seq,
+ uint32 extsize)
+{
+ int32 chunk_seq;
+ int32 last_chunk_seq = (extsize - 1) / TOAST_MAX_CHUNK_SIZE;
+ Pointer chunk;
+ bool isnull;
+ int32 chunksize;
+ int32 expected_size;
+
+ /* Sanity-check the sequence number. */
+ chunk_seq = DatumGetInt32(fastgetattr(toasttup, 2,
+ ctx->toast_rel->rd_att, &isnull));
+ if (isnull)
+ {
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u has toast chunk with null sequence number",
+ ta->toast_pointer.va_valueid));
+ return;
+ }
+ if (chunk_seq != *expected_chunk_seq)
+ {
+ /* Either the TOAST index is corrupt, or we don't have all chunks. */
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u index scan returned chunk %d when expecting chunk %d",
+ ta->toast_pointer.va_valueid,
+ chunk_seq, *expected_chunk_seq));
+ }
+ *expected_chunk_seq = chunk_seq + 1;
+
+ /* Sanity-check the chunk data. */
+ chunk = DatumGetPointer(fastgetattr(toasttup, 3,
+ ctx->toast_rel->rd_att, &isnull));
+ if (isnull)
+ {
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u chunk %d has null data",
+ ta->toast_pointer.va_valueid,
+ chunk_seq));
+ return;
+ }
+ if (!VARATT_IS_EXTENDED(chunk))
+ chunksize = VARSIZE(chunk) - VARHDRSZ;
+ else if (VARATT_IS_SHORT(chunk))
+ {
+ /*
+ * could happen due to heap_form_tuple doing its thing
+ */
+ chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+ }
+ else
+ {
+ /* should never happen */
+ uint32 header = ((varattrib_4b *) chunk)->va_4byte.va_header;
+
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u chunk %d has invalid varlena header %0x",
+ ta->toast_pointer.va_valueid,
+ chunk_seq, header));
+ return;
+ }
+
+ /*
+ * Some checks on the data we've found
+ */
+ if (chunk_seq > last_chunk_seq)
+ {
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u chunk %d follows last expected chunk %d",
+ ta->toast_pointer.va_valueid,
+ chunk_seq, last_chunk_seq));
+ return;
+ }
+
+ expected_size = chunk_seq < last_chunk_seq ? TOAST_MAX_CHUNK_SIZE
+ : extsize - (last_chunk_seq * TOAST_MAX_CHUNK_SIZE);
+
+ if (chunksize != expected_size)
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u chunk %d has size %u, but expected size %u",
+ ta->toast_pointer.va_valueid,
+ chunk_seq, chunksize, expected_size));
+}
+
+/*
+ * Check the current attribute as tracked in ctx, recording any corruption
+ * found in ctx->tupstore.
+ *
+ * This function follows the logic performed by heap_deform_tuple(), and in the
+ * case of a toasted value, optionally stores the toast pointer so later it can
+ * be checked following the logic of detoast_external_attr(), checking for any
+ * conditions that would result in either of those functions Asserting or
+ * crashing the backend. The checks performed by Asserts present in those two
+ * functions are also performed here and in check_toasted_attribute. In cases
+ * where those two functions are a bit cavalier in their assumptions about data
+ * being correct, we perform additional checks not present in either of those
+ * two functions. Where some condition is checked in both of those functions,
+ * we perform it here twice, as we parallel the logical flow of those two
+ * functions. The presence of duplicate checks seems a reasonable price to pay
+ * for keeping this code tightly coupled with the code it protects.
+ *
+ * Returns true if the tuple attribute is sane enough for processing to
+ * continue on to the next attribute, false otherwise.
+ */
+static bool
+check_tuple_attribute(HeapCheckContext *ctx)
+{
+ Datum attdatum;
+ struct varlena *attr;
+ char *tp; /* pointer to the tuple data */
+ uint16 infomask;
+ Form_pg_attribute thisatt;
+ struct varatt_external toast_pointer;
+
+ infomask = ctx->tuphdr->t_infomask;
+ thisatt = TupleDescAttr(RelationGetDescr(ctx->rel), ctx->attnum);
+
+ tp = (char *) ctx->tuphdr + ctx->tuphdr->t_hoff;
+
+ if (ctx->tuphdr->t_hoff + ctx->offset > ctx->lp_len)
+ {
+ report_corruption(ctx,
+ psprintf("attribute with length %u starts at offset %u beyond total tuple length %u",
+ thisatt->attlen,
+ ctx->tuphdr->t_hoff + ctx->offset,
+ ctx->lp_len));
+ return false;
+ }
+
+ /* Skip null values */
+ if (infomask & HEAP_HASNULL && att_isnull(ctx->attnum, ctx->tuphdr->t_bits))
+ return true;
+
+ /* Skip non-varlena values, but update offset first */
+ if (thisatt->attlen != -1)
+ {
+ ctx->offset = att_align_nominal(ctx->offset, thisatt->attalign);
+ ctx->offset = att_addlength_pointer(ctx->offset, thisatt->attlen,
+ tp + ctx->offset);
+ if (ctx->tuphdr->t_hoff + ctx->offset > ctx->lp_len)
+ {
+ report_corruption(ctx,
+ psprintf("attribute with length %u ends at offset %u beyond total tuple length %u",
+ thisatt->attlen,
+ ctx->tuphdr->t_hoff + ctx->offset,
+ ctx->lp_len));
+ return false;
+ }
+ return true;
+ }
+
+ /* Ok, we're looking at a varlena attribute. */
+ ctx->offset = att_align_pointer(ctx->offset, thisatt->attalign, -1,
+ tp + ctx->offset);
+
+ /* Get the (possibly corrupt) varlena datum */
+ attdatum = fetchatt(thisatt, tp + ctx->offset);
+
+ /*
+ * We have the datum, but we cannot decode it carelessly, as it may still
+ * be corrupt.
+ */
+
+ /*
+ * Check that VARTAG_SIZE won't hit a TrapMacro on a corrupt va_tag before
+ * risking a call into att_addlength_pointer
+ */
+ if (VARATT_IS_EXTERNAL(tp + ctx->offset))
+ {
+ uint8 va_tag = VARTAG_EXTERNAL(tp + ctx->offset);
+
+ if (va_tag != VARTAG_ONDISK)
+ {
+ report_corruption(ctx,
+ psprintf("toasted attribute has unexpected TOAST tag %u",
+ va_tag));
+ /* We can't know where the next attribute begins */
+ return false;
+ }
+ }
+
+ /* Ok, should be safe now */
+ ctx->offset = att_addlength_pointer(ctx->offset, thisatt->attlen,
+ tp + ctx->offset);
+
+ if (ctx->tuphdr->t_hoff + ctx->offset > ctx->lp_len)
+ {
+ report_corruption(ctx,
+ psprintf("attribute with length %u ends at offset %u beyond total tuple length %u",
+ thisatt->attlen,
+ ctx->tuphdr->t_hoff + ctx->offset,
+ ctx->lp_len));
+
+ return false;
+ }
+
+ /*
+ * heap_deform_tuple would be done with this attribute at this point,
+ * having stored it in values[], and would continue to the next attribute.
+ * We go further, because we need to check if the toast datum is corrupt.
+ */
+
+ attr = (struct varlena *) DatumGetPointer(attdatum);
+
+ /*
+ * Now we follow the logic of detoast_external_attr(), with the same
+ * caveats about being paranoid about corruption.
+ */
+
+ /* Skip values that are not external */
+ if (!VARATT_IS_EXTERNAL(attr))
+ return true;
+
+ /* It is external, and we're looking at a page on disk */
+
+ /*
+ * Must copy attr into toast_pointer for alignment considerations
+ */
+ VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+ /* Toasted attributes too large to be untoasted should never be stored */
+ if (toast_pointer.va_rawsize > VARLENA_SIZE_LIMIT)
+ report_corruption(ctx,
+ psprintf("toast value %u rawsize %d exceeds limit %d",
+ toast_pointer.va_valueid,
+ toast_pointer.va_rawsize,
+ VARLENA_SIZE_LIMIT));
+
+ if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+ {
+ ToastCompressionId cmid;
+ bool valid = false;
+
+ /* Compressed attributes should have a valid compression method */
+ cmid = TOAST_COMPRESS_METHOD(&toast_pointer);
+ switch (cmid)
+ {
+ /* List of all valid compression method IDs */
+ case TOAST_PGLZ_COMPRESSION_ID:
+ case TOAST_LZ4_COMPRESSION_ID:
+ valid = true;
+ break;
+
+ /* Recognized but invalid compression method ID */
+ case TOAST_INVALID_COMPRESSION_ID:
+ break;
+
+ /* Intentionally no default here */
+ }
+ if (!valid)
+ report_corruption(ctx,
+ psprintf("toast value %u has invalid compression method id %d",
+ toast_pointer.va_valueid, cmid));
+ }
+
+ /* The tuple header better claim to contain toasted values */
+ if (!(infomask & HEAP_HASEXTERNAL))
+ {
+ report_corruption(ctx,
+ psprintf("toast value %u is external but tuple header flag HEAP_HASEXTERNAL not set",
+ toast_pointer.va_valueid));
+ return true;
+ }
+
+ /* The relation better have a toast table */
+ if (!ctx->rel->rd_rel->reltoastrelid)
+ {
+ report_corruption(ctx,
+ psprintf("toast value %u is external but relation has no toast relation",
+ toast_pointer.va_valueid));
+ return true;
+ }
+
+ /* If we were told to skip toast checking, then we're done. */
+ if (ctx->toast_rel == NULL)
+ return true;
+
+ /*
+ * If this tuple is eligible to be pruned, we cannot check the toast.
+ * Otherwise, we push a copy of the toast tuple so we can check it after
+ * releasing the main table buffer lock.
+ */
+ if (!ctx->tuple_could_be_pruned)
+ {
+ ToastedAttribute *ta;
+
+ ta = (ToastedAttribute *) palloc0(sizeof(ToastedAttribute));
+
+ VARATT_EXTERNAL_GET_POINTER(ta->toast_pointer, attr);
+ ta->blkno = ctx->blkno;
+ ta->offnum = ctx->offnum;
+ ta->attnum = ctx->attnum;
+ ctx->toasted_attributes = lappend(ctx->toasted_attributes, ta);
+ }
+
+ return true;
+}
+
+/*
+ * For each attribute collected in ctx->toasted_attributes, look up the value
+ * in the toast table and perform checks on it. This function should only be
+ * called on toast pointers which cannot be vacuumed away during our
+ * processing.
+ */
+static void
+check_toasted_attribute(HeapCheckContext *ctx, ToastedAttribute *ta)
+{
+ SnapshotData SnapshotToast;
+ ScanKeyData toastkey;
+ SysScanDesc toastscan;
+ bool found_toasttup;
+ HeapTuple toasttup;
+ uint32 extsize;
+ int32 expected_chunk_seq = 0;
+ int32 last_chunk_seq;
+
+ extsize = VARATT_EXTERNAL_GET_EXTSIZE(ta->toast_pointer);
+ last_chunk_seq = (extsize - 1) / TOAST_MAX_CHUNK_SIZE;
+
+ /*
+ * Setup a scan key to find chunks in toast table with matching va_valueid
+ */
+ ScanKeyInit(&toastkey,
+ (AttrNumber) 1,
+ BTEqualStrategyNumber, F_OIDEQ,
+ ObjectIdGetDatum(ta->toast_pointer.va_valueid));
+
+ /*
+ * Check if any chunks for this toasted object exist in the toast table,
+ * accessible via the index.
+ */
+ init_toast_snapshot(&SnapshotToast);
+ toastscan = systable_beginscan_ordered(ctx->toast_rel,
+ ctx->valid_toast_index,
+ &SnapshotToast, 1,
+ &toastkey);
+ found_toasttup = false;
+ while ((toasttup =
+ systable_getnext_ordered(toastscan,
+ ForwardScanDirection)) != NULL)
+ {
+ found_toasttup = true;
+ check_toast_tuple(toasttup, ctx, ta, &expected_chunk_seq, extsize);
+ }
+ systable_endscan_ordered(toastscan);
+
+ if (!found_toasttup)
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u not found in toast table",
+ ta->toast_pointer.va_valueid));
+ else if (expected_chunk_seq <= last_chunk_seq)
+ report_toast_corruption(ctx, ta,
+ psprintf("toast value %u was expected to end at chunk %d, but ended while expecting chunk %d",
+ ta->toast_pointer.va_valueid,
+ last_chunk_seq, expected_chunk_seq));
+}
+
+/*
+ * Check the current tuple as tracked in ctx, recording any corruption found in
+ * ctx->tupstore.
+ */
+static void
+check_tuple(HeapCheckContext *ctx)
+{
+ /*
+ * Check various forms of tuple header corruption, and if the header is
+ * too corrupt, do not continue with other checks.
+ */
+ if (!check_tuple_header(ctx))
+ return;
+
+ /*
+ * Check tuple visibility. If the inserting transaction aborted, we
+ * cannot assume our relation description matches the tuple structure, and
+ * therefore cannot check it.
+ */
+ if (!check_tuple_visibility(ctx))
+ return;
+
+ /*
+ * The tuple is visible, so it must be compatible with the current version
+ * of the relation descriptor. It might have fewer columns than are
+ * present in the relation descriptor, but it cannot have more.
+ */
+ if (RelationGetDescr(ctx->rel)->natts < ctx->natts)
+ {
+ report_corruption(ctx,
+ psprintf("number of attributes %u exceeds maximum expected for table %u",
+ ctx->natts,
+ RelationGetDescr(ctx->rel)->natts));
+ return;
+ }
+
+ /*
+ * Check each attribute unless we hit corruption that confuses what to do
+ * next, at which point we abort further attribute checks for this tuple.
+ * Note that we don't abort for all types of corruption, only for those
+ * types where we don't know how to continue. We also don't abort the
+ * checking of toasted attributes collected from the tuple prior to
+ * aborting. Those will still be checked later along with other toasted
+ * attributes collected from the page.
+ */
+ ctx->offset = 0;
+ for (ctx->attnum = 0; ctx->attnum < ctx->natts; ctx->attnum++)
+ if (!check_tuple_attribute(ctx))
+ break; /* cannot continue */
+
+ /* revert attnum to -1 until we again examine individual attributes */
+ ctx->attnum = -1;
+}
+
+/*
+ * Convert a TransactionId into a FullTransactionId using our cached values of
+ * the valid transaction ID range. It is the caller's responsibility to have
+ * already updated the cached values, if necessary.
+ */
+static FullTransactionId
+FullTransactionIdFromXidAndCtx(TransactionId xid, const HeapCheckContext *ctx)
+{
+ uint64 nextfxid_i;
+ int32 diff;
+ FullTransactionId fxid;
+
+ Assert(TransactionIdIsNormal(ctx->next_xid));
+ Assert(FullTransactionIdIsNormal(ctx->next_fxid));
+ Assert(XidFromFullTransactionId(ctx->next_fxid) == ctx->next_xid);
+
+ if (!TransactionIdIsNormal(xid))
+ return FullTransactionIdFromEpochAndXid(0, xid);
+
+ nextfxid_i = U64FromFullTransactionId(ctx->next_fxid);
+
+ /* compute the 32bit modulo difference */
+ diff = (int32) (ctx->next_xid - xid);
+
+ /*
+ * In cases of corruption we might see a 32bit xid that is before epoch
+ * 0. We can't represent that as a 64bit xid, due to 64bit xids being
+ * unsigned integers, without the modulo arithmetic of 32bit xid. There's
+ * no really nice way to deal with that, but it works ok enough to use
+ * FirstNormalFullTransactionId in that case, as a freshly initdb'd
+ * cluster already has a newer horizon.
+ */
+ if (diff > 0 && (nextfxid_i - FirstNormalTransactionId) < (int64) diff)
+ {
+ Assert(EpochFromFullTransactionId(ctx->next_fxid) == 0);
+ fxid = FirstNormalFullTransactionId;
+ }
+ else
+ fxid = FullTransactionIdFromU64(nextfxid_i - diff);
+
+ Assert(FullTransactionIdIsNormal(fxid));
+ return fxid;
+}
+
+/*
+ * Update our cached range of valid transaction IDs.
+ */
+static void
+update_cached_xid_range(HeapCheckContext *ctx)
+{
+ /* Make cached copies */
+ LWLockAcquire(XidGenLock, LW_SHARED);
+ ctx->next_fxid = ShmemVariableCache->nextXid;
+ ctx->oldest_xid = ShmemVariableCache->oldestXid;
+ LWLockRelease(XidGenLock);
+
+ /* And compute alternate versions of the same */
+ ctx->next_xid = XidFromFullTransactionId(ctx->next_fxid);
+ ctx->oldest_fxid = FullTransactionIdFromXidAndCtx(ctx->oldest_xid, ctx);
+}
+
+/*
+ * Update our cached range of valid multitransaction IDs.
+ */
+static void
+update_cached_mxid_range(HeapCheckContext *ctx)
+{
+ ReadMultiXactIdRange(&ctx->oldest_mxact, &ctx->next_mxact);
+}
+
+/*
+ * Return whether the given FullTransactionId is within our cached valid
+ * transaction ID range.
+ */
+static inline bool
+fxid_in_cached_range(FullTransactionId fxid, const HeapCheckContext *ctx)
+{
+ return (FullTransactionIdPrecedesOrEquals(ctx->oldest_fxid, fxid) &&
+ FullTransactionIdPrecedes(fxid, ctx->next_fxid));
+}
+
+/*
+ * Checks whether a multitransaction ID is in the cached valid range, returning
+ * the nature of the range violation, if any.
+ */
+static XidBoundsViolation
+check_mxid_in_range(MultiXactId mxid, HeapCheckContext *ctx)
+{
+ if (!TransactionIdIsValid(mxid))
+ return XID_INVALID;
+ if (MultiXactIdPrecedes(mxid, ctx->relminmxid))
+ return XID_PRECEDES_RELMIN;
+ if (MultiXactIdPrecedes(mxid, ctx->oldest_mxact))
+ return XID_PRECEDES_CLUSTERMIN;
+ if (MultiXactIdPrecedesOrEquals(ctx->next_mxact, mxid))
+ return XID_IN_FUTURE;
+ return XID_BOUNDS_OK;
+}
+
+/*
+ * Checks whether the given mxid is valid to appear in the heap being checked,
+ * returning the nature of the range violation, if any.
+ *
+ * This function attempts to return quickly by caching the known valid mxid
+ * range in ctx. Callers should already have performed the initial setup of
+ * the cache prior to the first call to this function.
+ */
+static XidBoundsViolation
+check_mxid_valid_in_rel(MultiXactId mxid, HeapCheckContext *ctx)
+{
+ XidBoundsViolation result;
+
+ result = check_mxid_in_range(mxid, ctx);
+ if (result == XID_BOUNDS_OK)
+ return XID_BOUNDS_OK;
+
+ /* The range may have advanced. Recheck. */
+ update_cached_mxid_range(ctx);
+ return check_mxid_in_range(mxid, ctx);
+}
+
+/*
+ * Checks whether the given transaction ID is (or was recently) valid to appear
+ * in the heap being checked, or whether it is too old or too new to appear in
+ * the relation, returning information about the nature of the bounds violation.
+ *
+ * We cache the range of valid transaction IDs. If xid is in that range, we
+ * conclude that it is valid, even though concurrent changes to the table might
+ * invalidate it under certain corrupt conditions. (For example, if the table
+ * contains corrupt all-frozen bits, a concurrent vacuum might skip the page(s)
+ * containing the xid and then truncate clog and advance the relfrozenxid
+ * beyond xid.) Reporting the xid as valid under such conditions seems
+ * acceptable, since if we had checked it earlier in our scan it would have
+ * truly been valid at that time.
+ *
+ * If the status argument is not NULL, and if and only if the transaction ID
+ * appears to be valid in this relation, the status argument will be set with
+ * the commit status of the transaction ID.
+ */
+static XidBoundsViolation
+get_xid_status(TransactionId xid, HeapCheckContext *ctx,
+ XidCommitStatus *status)
+{
+ FullTransactionId fxid;
+ FullTransactionId clog_horizon;
+
+ /* Quick check for special xids */
+ if (!TransactionIdIsValid(xid))
+ return XID_INVALID;
+ else if (xid == BootstrapTransactionId || xid == FrozenTransactionId)
+ {
+ if (status != NULL)
+ *status = XID_COMMITTED;
+ return XID_BOUNDS_OK;
+ }
+
+ /* Check if the xid is within bounds */
+ fxid = FullTransactionIdFromXidAndCtx(xid, ctx);
+ if (!fxid_in_cached_range(fxid, ctx))
+ {
+ /*
+ * We may have been checking against stale values. Update the cached
+ * range to be sure, and since we relied on the cached range when we
+ * performed the full xid conversion, reconvert.
+ */
+ update_cached_xid_range(ctx);
+ fxid = FullTransactionIdFromXidAndCtx(xid, ctx);
+ }
+
+ if (FullTransactionIdPrecedesOrEquals(ctx->next_fxid, fxid))
+ return XID_IN_FUTURE;
+ if (FullTransactionIdPrecedes(fxid, ctx->oldest_fxid))
+ return XID_PRECEDES_CLUSTERMIN;
+ if (FullTransactionIdPrecedes(fxid, ctx->relfrozenfxid))
+ return XID_PRECEDES_RELMIN;
+
+ /* Early return if the caller does not request clog checking */
+ if (status == NULL)
+ return XID_BOUNDS_OK;
+
+ /* Early return if we just checked this xid in a prior call */
+ if (xid == ctx->cached_xid)
+ {
+ *status = ctx->cached_status;
+ return XID_BOUNDS_OK;
+ }
+
+ *status = XID_COMMITTED;
+ LWLockAcquire(XactTruncationLock, LW_SHARED);
+ clog_horizon =
+ FullTransactionIdFromXidAndCtx(ShmemVariableCache->oldestClogXid,
+ ctx);
+ if (FullTransactionIdPrecedesOrEquals(clog_horizon, fxid))
+ {
+ if (TransactionIdIsCurrentTransactionId(xid))
+ *status = XID_IS_CURRENT_XID;
+ else if (TransactionIdIsInProgress(xid))
+ *status = XID_IN_PROGRESS;
+ else if (TransactionIdDidCommit(xid))
+ *status = XID_COMMITTED;
+ else
+ *status = XID_ABORTED;
+ }
+ LWLockRelease(XactTruncationLock);
+ ctx->cached_xid = xid;
+ ctx->cached_status = *status;
+ return XID_BOUNDS_OK;
+}
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
new file mode 100644
index 0000000..1886bd2
--- /dev/null
+++ b/contrib/amcheck/verify_nbtree.c
@@ -0,0 +1,3346 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_nbtree.c
+ * Verifies the integrity of nbtree indexes based on invariants.
+ *
+ * For B-Tree indexes, verification includes checking that each page in the
+ * target index has items in logical order as reported by an insertion scankey
+ * (the insertion scankey sort-wise NULL semantics are needed for
+ * verification).
+ *
+ * When index-to-heap verification is requested, a Bloom filter is used to
+ * fingerprint all tuples in the target index, as the index is traversed to
+ * verify its structure. A heap scan later uses Bloom filter probes to verify
+ * that every visible heap tuple has a matching index tuple.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * contrib/amcheck/verify_nbtree.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "access/nbtree.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "access/xact.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "catalog/pg_opfamily_d.h"
+#include "commands/tablecmds.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "miscadmin.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/snapmgr.h"
+
+
+PG_MODULE_MAGIC;
+
+/*
+ * A B-Tree cannot possibly have this many levels, since there must be one
+ * block per level, which is bound by the range of BlockNumber:
+ */
+#define InvalidBtreeLevel ((uint32) InvalidBlockNumber)
+#define BTreeTupleGetNKeyAtts(itup, rel) \
+ Min(IndexRelationGetNumberOfKeyAttributes(rel), BTreeTupleGetNAtts(itup, rel))
+
+/*
+ * State associated with verifying a B-Tree index
+ *
+ * target is the point of reference for a verification operation.
+ *
+ * Other B-Tree pages may be allocated, but those are always auxiliary (e.g.,
+ * they are current target's child pages). Conceptually, problems are only
+ * ever found in the current target page (or for a particular heap tuple during
+ * heapallindexed verification). Each page found by verification's left/right,
+ * top/bottom scan becomes the target exactly once.
+ */
+typedef struct BtreeCheckState
+{
+ /*
+ * Unchanging state, established at start of verification:
+ */
+
+ /* B-Tree Index Relation and associated heap relation */
+ Relation rel;
+ Relation heaprel;
+ /* rel is heapkeyspace index? */
+ bool heapkeyspace;
+ /* ShareLock held on heap/index, rather than AccessShareLock? */
+ bool readonly;
+ /* Also verifying heap has no unindexed tuples? */
+ bool heapallindexed;
+ /* Also making sure non-pivot tuples can be found by new search? */
+ bool rootdescend;
+ /* Per-page context */
+ MemoryContext targetcontext;
+ /* Buffer access strategy */
+ BufferAccessStrategy checkstrategy;
+
+ /*
+ * Mutable state, for verification of particular page:
+ */
+
+ /* Current target page */
+ Page target;
+ /* Target block number */
+ BlockNumber targetblock;
+ /* Target page's LSN */
+ XLogRecPtr targetlsn;
+
+ /*
+ * Low key: high key of left sibling of target page. Used only for child
+ * verification. So, 'lowkey' is kept only when 'readonly' is set.
+ */
+ IndexTuple lowkey;
+
+ /*
+ * The rightlink and incomplete split flag of block one level down to the
+ * target page, which was visited last time via downlink from taget page.
+ * We use it to check for missing downlinks.
+ */
+ BlockNumber prevrightlink;
+ bool previncompletesplit;
+
+ /*
+ * Mutable state, for optional heapallindexed verification:
+ */
+
+ /* Bloom filter fingerprints B-Tree index */
+ bloom_filter *filter;
+ /* Debug counter */
+ int64 heaptuplespresent;
+} BtreeCheckState;
+
+/*
+ * Starting point for verifying an entire B-Tree index level
+ */
+typedef struct BtreeLevel
+{
+ /* Level number (0 is leaf page level). */
+ uint32 level;
+
+ /* Left most block on level. Scan of level begins here. */
+ BlockNumber leftmost;
+
+ /* Is this level reported as "true" root level by meta page? */
+ bool istruerootlevel;
+} BtreeLevel;
+
+PG_FUNCTION_INFO_V1(bt_index_check);
+PG_FUNCTION_INFO_V1(bt_index_parent_check);
+
+static void bt_index_check_internal(Oid indrelid, bool parentcheck,
+ bool heapallindexed, bool rootdescend);
+static inline void btree_index_checkable(Relation rel);
+static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_check_every_level(Relation rel, Relation heaprel,
+ bool heapkeyspace, bool readonly, bool heapallindexed,
+ bool rootdescend);
+static BtreeLevel bt_check_level_from_leftmost(BtreeCheckState *state,
+ BtreeLevel level);
+static bool bt_leftmost_ignoring_half_dead(BtreeCheckState *state,
+ BlockNumber start,
+ BTPageOpaque start_opaque);
+static void bt_recheck_sibling_links(BtreeCheckState *state,
+ BlockNumber btpo_prev_from_target,
+ BlockNumber leftcurrent);
+static void bt_target_page_check(BtreeCheckState *state);
+static BTScanInsert bt_right_page_check_scankey(BtreeCheckState *state);
+static void bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
+ OffsetNumber downlinkoffnum);
+static void bt_child_highkey_check(BtreeCheckState *state,
+ OffsetNumber target_downlinkoffnum,
+ Page loaded_child,
+ uint32 target_level);
+static void bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
+ BlockNumber targetblock, Page target);
+static void bt_tuple_present_callback(Relation index, ItemPointer tid,
+ Datum *values, bool *isnull,
+ bool tupleIsAlive, void *checkstate);
+static IndexTuple bt_normalize_tuple(BtreeCheckState *state,
+ IndexTuple itup);
+static inline IndexTuple bt_posting_plain_tuple(IndexTuple itup, int n);
+static bool bt_rootdescend(BtreeCheckState *state, IndexTuple itup);
+static inline bool offset_is_negative_infinity(BTPageOpaque opaque,
+ OffsetNumber offset);
+static inline bool invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
+ OffsetNumber upperbound);
+static inline bool invariant_leq_offset(BtreeCheckState *state,
+ BTScanInsert key,
+ OffsetNumber upperbound);
+static inline bool invariant_g_offset(BtreeCheckState *state, BTScanInsert key,
+ OffsetNumber lowerbound);
+static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
+ BTScanInsert key,
+ BlockNumber nontargetblock,
+ Page nontarget,
+ OffsetNumber upperbound);
+static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
+static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
+ IndexTuple itup);
+static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
+ Page page, OffsetNumber offset);
+static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
+ IndexTuple itup, bool nonpivot);
+static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
+
+/*
+ * bt_index_check(index regclass, heapallindexed boolean)
+ *
+ * Verify integrity of B-Tree index.
+ *
+ * Acquires AccessShareLock on heap & index relations. Does not consider
+ * invariants that exist between parent/child pages. Optionally verifies
+ * that heap does not contain any unindexed or incorrectly indexed tuples.
+ */
+Datum
+bt_index_check(PG_FUNCTION_ARGS)
+{
+ Oid indrelid = PG_GETARG_OID(0);
+ bool heapallindexed = false;
+
+ if (PG_NARGS() == 2)
+ heapallindexed = PG_GETARG_BOOL(1);
+
+ bt_index_check_internal(indrelid, false, heapallindexed, false);
+
+ PG_RETURN_VOID();
+}
+
+/*
+ * bt_index_parent_check(index regclass, heapallindexed boolean)
+ *
+ * Verify integrity of B-Tree index.
+ *
+ * Acquires ShareLock on heap & index relations. Verifies that downlinks in
+ * parent pages are valid lower bounds on child pages. Optionally verifies
+ * that heap does not contain any unindexed or incorrectly indexed tuples.
+ */
+Datum
+bt_index_parent_check(PG_FUNCTION_ARGS)
+{
+ Oid indrelid = PG_GETARG_OID(0);
+ bool heapallindexed = false;
+ bool rootdescend = false;
+
+ if (PG_NARGS() >= 2)
+ heapallindexed = PG_GETARG_BOOL(1);
+ if (PG_NARGS() == 3)
+ rootdescend = PG_GETARG_BOOL(2);
+
+ bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+
+ PG_RETURN_VOID();
+}
+
+/*
+ * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
+ */
+static void
+bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
+ bool rootdescend)
+{
+ Oid heapid;
+ Relation indrel;
+ Relation heaprel;
+ LOCKMODE lockmode;
+ Oid save_userid;
+ int save_sec_context;
+ int save_nestlevel;
+
+ if (parentcheck)
+ lockmode = ShareLock;
+ else
+ lockmode = AccessShareLock;
+
+ /*
+ * We must lock table before index to avoid deadlocks. However, if the
+ * passed indrelid isn't an index then IndexGetRelation() will fail.
+ * Rather than emitting a not-very-helpful error message, postpone
+ * complaining, expecting that the is-it-an-index test below will fail.
+ *
+ * In hot standby mode this will raise an error when parentcheck is true.
+ */
+ heapid = IndexGetRelation(indrelid, true);
+ if (OidIsValid(heapid))
+ {
+ heaprel = table_open(heapid, lockmode);
+
+ /*
+ * Switch to the table owner's userid, so that any index functions are
+ * run as that user. Also lock down security-restricted operations
+ * and arrange to make GUC variable changes local to this command.
+ */
+ GetUserIdAndSecContext(&save_userid, &save_sec_context);
+ SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+ save_sec_context | SECURITY_RESTRICTED_OPERATION);
+ save_nestlevel = NewGUCNestLevel();
+ }
+ else
+ {
+ heaprel = NULL;
+ /* Set these just to suppress "uninitialized variable" warnings */
+ save_userid = InvalidOid;
+ save_sec_context = -1;
+ save_nestlevel = -1;
+ }
+
+ /*
+ * Open the target index relations separately (like relation_openrv(), but
+ * with heap relation locked first to prevent deadlocking). In hot
+ * standby mode this will raise an error when parentcheck is true.
+ *
+ * There is no need for the usual indcheckxmin usability horizon test
+ * here, even in the heapallindexed case, because index undergoing
+ * verification only needs to have entries for a new transaction snapshot.
+ * (If this is a parentcheck verification, there is no question about
+ * committed or recently dead heap tuples lacking index entries due to
+ * concurrent activity.)
+ */
+ indrel = index_open(indrelid, lockmode);
+
+ /*
+ * Since we did the IndexGetRelation call above without any lock, it's
+ * barely possible that a race against an index drop/recreation could have
+ * netted us the wrong table.
+ */
+ if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+ ereport(ERROR,
+ (errcode(ERRCODE_UNDEFINED_TABLE),
+ errmsg("could not open parent table of index \"%s\"",
+ RelationGetRelationName(indrel))));
+
+ /* Relation suitable for checking as B-Tree? */
+ btree_index_checkable(indrel);
+
+ if (btree_index_mainfork_expected(indrel))
+ {
+ bool heapkeyspace,
+ allequalimage;
+
+ if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index \"%s\" lacks a main relation fork",
+ RelationGetRelationName(indrel))));
+
+ /* Extract metadata from metapage, and sanitize it in passing */
+ _bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+ if (allequalimage && !heapkeyspace)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+ RelationGetRelationName(indrel))));
+ if (allequalimage && !_bt_allequalimage(indrel, false))
+ {
+ bool has_interval_ops = false;
+
+ for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+ if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+ has_interval_ops = true;
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+ RelationGetRelationName(indrel)),
+ has_interval_ops
+ ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+ : 0));
+ }
+
+ /* Check index, possibly against table it is an index on */
+ bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
+ heapallindexed, rootdescend);
+ }
+
+ /* Roll back any GUC changes executed by index functions */
+ AtEOXact_GUC(false, save_nestlevel);
+
+ /* Restore userid and security context */
+ SetUserIdAndSecContext(save_userid, save_sec_context);
+
+ /*
+ * Release locks early. That's ok here because nothing in the called
+ * routines will trigger shared cache invalidations to be sent, so we can
+ * relax the usual pattern of only releasing locks after commit.
+ */
+ index_close(indrel, lockmode);
+ if (heaprel)
+ table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as a B-Tree
+ * index.
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+static inline void
+btree_index_checkable(Relation rel)
+{
+ if (rel->rd_rel->relkind != RELKIND_INDEX ||
+ rel->rd_rel->relam != BTREE_AM_OID)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("only B-Tree indexes are supported as targets for verification"),
+ errdetail("Relation \"%s\" is not a B-Tree index.",
+ RelationGetRelationName(rel))));
+
+ if (RELATION_IS_OTHER_TEMP(rel))
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot access temporary tables of other sessions"),
+ errdetail("Index \"%s\" is associated with temporary relation.",
+ RelationGetRelationName(rel))));
+
+ if (!rel->rd_index->indisvalid)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot check index \"%s\"",
+ RelationGetRelationName(rel)),
+ errdetail("Index is not valid.")));
+}
+
+/*
+ * Check if B-Tree index relation should have a file for its main relation
+ * fork. Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify. We behave as if the
+ * relation is empty.
+ *
+ * NB: Caller should call btree_index_checkable() before calling here.
+ */
+static inline bool
+btree_index_mainfork_expected(Relation rel)
+{
+ if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+ !RecoveryInProgress())
+ return true;
+
+ ereport(DEBUG1,
+ (errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+ errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+ RelationGetRelationName(rel))));
+
+ return false;
+}
+
+/*
+ * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
+ * logical order, verifying invariants as it goes. Optionally, verification
+ * checks if the heap relation contains any tuples that are not represented in
+ * the index but should be.
+ *
+ * It is the caller's responsibility to acquire appropriate heavyweight lock on
+ * the index relation, and advise us if extra checks are safe when a ShareLock
+ * is held. (A lock of the same type must also have been acquired on the heap
+ * relation.)
+ *
+ * A ShareLock is generally assumed to prevent any kind of physical
+ * modification to the index structure, including modifications that VACUUM may
+ * make. This does not include setting of the LP_DEAD bit by concurrent index
+ * scans, although that is just metadata that is not able to directly affect
+ * any check performed here. Any concurrent process that might act on the
+ * LP_DEAD bit being set (recycle space) requires a heavyweight lock that
+ * cannot be held while we hold a ShareLock. (Besides, even if that could
+ * happen, the ad-hoc recycling when a page might otherwise split is performed
+ * per-page, and requires an exclusive buffer lock, which wouldn't cause us
+ * trouble. _bt_delitems_vacuum() may only delete leaf items, and so the extra
+ * parent/child check cannot be affected.)
+ */
+static void
+bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
+ bool readonly, bool heapallindexed, bool rootdescend)
+{
+ BtreeCheckState *state;
+ Page metapage;
+ BTMetaPageData *metad;
+ uint32 previouslevel;
+ BtreeLevel current;
+ Snapshot snapshot = SnapshotAny;
+
+ if (!readonly)
+ elog(DEBUG1, "verifying consistency of tree structure for index \"%s\"",
+ RelationGetRelationName(rel));
+ else
+ elog(DEBUG1, "verifying consistency of tree structure for index \"%s\" with cross-level checks",
+ RelationGetRelationName(rel));
+
+ /*
+ * This assertion matches the one in index_getnext_tid(). See page
+ * recycling/"visible to everyone" notes in nbtree README.
+ */
+ Assert(TransactionIdIsValid(RecentXmin));
+
+ /*
+ * Initialize state for entire verification operation
+ */
+ state = palloc0(sizeof(BtreeCheckState));
+ state->rel = rel;
+ state->heaprel = heaprel;
+ state->heapkeyspace = heapkeyspace;
+ state->readonly = readonly;
+ state->heapallindexed = heapallindexed;
+ state->rootdescend = rootdescend;
+
+ if (state->heapallindexed)
+ {
+ int64 total_pages;
+ int64 total_elems;
+ uint64 seed;
+
+ /*
+ * Size Bloom filter based on estimated number of tuples in index,
+ * while conservatively assuming that each block must contain at least
+ * MaxTIDsPerBTreePage / 3 "plain" tuples -- see
+ * bt_posting_plain_tuple() for definition, and details of how posting
+ * list tuples are handled.
+ */
+ total_pages = RelationGetNumberOfBlocks(rel);
+ total_elems = Max(total_pages * (MaxTIDsPerBTreePage / 3),
+ (int64) state->rel->rd_rel->reltuples);
+ /* Generate a random seed to avoid repetition */
+ seed = pg_prng_uint64(&pg_global_prng_state);
+ /* Create Bloom filter to fingerprint index */
+ state->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+ state->heaptuplespresent = 0;
+
+ /*
+ * Register our own snapshot in !readonly case, rather than asking
+ * table_index_build_scan() to do this for us later. This needs to
+ * happen before index fingerprinting begins, so we can later be
+ * certain that index fingerprinting should have reached all tuples
+ * returned by table_index_build_scan().
+ */
+ if (!state->readonly)
+ {
+ snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+ /*
+ * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+ * READ COMMITTED mode. A new snapshot is guaranteed to have all
+ * the entries it requires in the index.
+ *
+ * We must defend against the possibility that an old xact
+ * snapshot was returned at higher isolation levels when that
+ * snapshot is not safe for index scans of the target index. This
+ * is possible when the snapshot sees tuples that are before the
+ * index's indcheckxmin horizon. Throwing an error here should be
+ * very rare. It doesn't seem worth using a secondary snapshot to
+ * avoid this.
+ */
+ if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+ !TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+ snapshot->xmin))
+ ereport(ERROR,
+ (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+ errmsg("index \"%s\" cannot be verified using transaction snapshot",
+ RelationGetRelationName(rel))));
+ }
+ }
+
+ Assert(!state->rootdescend || state->readonly);
+ if (state->rootdescend && !state->heapkeyspace)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot verify that tuples from index \"%s\" can each be found by an independent index search",
+ RelationGetRelationName(rel)),
+ errhint("Only B-Tree version 4 indexes support rootdescend verification.")));
+
+ /* Create context for page */
+ state->targetcontext = AllocSetContextCreate(CurrentMemoryContext,
+ "amcheck context",
+ ALLOCSET_DEFAULT_SIZES);
+ state->checkstrategy = GetAccessStrategy(BAS_BULKREAD);
+
+ /* Get true root block from meta-page */
+ metapage = palloc_btree_page(state, BTREE_METAPAGE);
+ metad = BTPageGetMeta(metapage);
+
+ /*
+ * Certain deletion patterns can result in "skinny" B-Tree indexes, where
+ * the fast root and true root differ.
+ *
+ * Start from the true root, not the fast root, unlike conventional index
+ * scans. This approach is more thorough, and removes the risk of
+ * following a stale fast root from the meta page.
+ */
+ if (metad->btm_fastroot != metad->btm_root)
+ ereport(DEBUG1,
+ (errcode(ERRCODE_NO_DATA),
+ errmsg_internal("harmless fast root mismatch in index \"%s\"",
+ RelationGetRelationName(rel)),
+ errdetail_internal("Fast root block %u (level %u) differs from true root block %u (level %u).",
+ metad->btm_fastroot, metad->btm_fastlevel,
+ metad->btm_root, metad->btm_level)));
+
+ /*
+ * Starting at the root, verify every level. Move left to right, top to
+ * bottom. Note that there may be no pages other than the meta page (meta
+ * page can indicate that root is P_NONE when the index is totally empty).
+ */
+ previouslevel = InvalidBtreeLevel;
+ current.level = metad->btm_level;
+ current.leftmost = metad->btm_root;
+ current.istruerootlevel = true;
+ while (current.leftmost != P_NONE)
+ {
+ /*
+ * Verify this level, and get left most page for next level down, if
+ * not at leaf level
+ */
+ current = bt_check_level_from_leftmost(state, current);
+
+ if (current.leftmost == InvalidBlockNumber)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index \"%s\" has no valid pages on level below %u or first level",
+ RelationGetRelationName(rel), previouslevel)));
+
+ previouslevel = current.level;
+ }
+
+ /*
+ * * Check whether heap contains unindexed/malformed tuples *
+ */
+ if (state->heapallindexed)
+ {
+ IndexInfo *indexinfo = BuildIndexInfo(state->rel);
+ TableScanDesc scan;
+
+ /*
+ * Create our own scan for table_index_build_scan(), rather than
+ * getting it to do so for us. This is required so that we can
+ * actually use the MVCC snapshot registered earlier in !readonly
+ * case.
+ *
+ * Note that table_index_build_scan() calls heap_endscan() for us.
+ */
+ scan = table_beginscan_strat(state->heaprel, /* relation */
+ snapshot, /* snapshot */
+ 0, /* number of keys */
+ NULL, /* scan key */
+ true, /* buffer access strategy OK */
+ true); /* syncscan OK? */
+
+ /*
+ * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY
+ * behaves in !readonly case.
+ *
+ * It's okay that we don't actually use the same lock strength for the
+ * heap relation as any other ii_Concurrent caller would in !readonly
+ * case. We have no reason to care about a concurrent VACUUM
+ * operation, since there isn't going to be a second scan of the heap
+ * that needs to be sure that there was no concurrent recycling of
+ * TIDs.
+ */
+ indexinfo->ii_Concurrent = !state->readonly;
+
+ /*
+ * Don't wait for uncommitted tuple xact commit/abort when index is a
+ * unique index on a catalog (or an index used by an exclusion
+ * constraint). This could otherwise happen in the readonly case.
+ */
+ indexinfo->ii_Unique = false;
+ indexinfo->ii_ExclusionOps = NULL;
+ indexinfo->ii_ExclusionProcs = NULL;
+ indexinfo->ii_ExclusionStrats = NULL;
+
+ elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+ RelationGetRelationName(state->rel),
+ RelationGetRelationName(state->heaprel));
+
+ table_index_build_scan(state->heaprel, state->rel, indexinfo, true, false,
+ bt_tuple_present_callback, (void *) state, scan);
+
+ ereport(DEBUG1,
+ (errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+ state->heaptuplespresent, RelationGetRelationName(heaprel),
+ 100.0 * bloom_prop_bits_set(state->filter))));
+
+ if (snapshot != SnapshotAny)
+ UnregisterSnapshot(snapshot);
+
+ bloom_free(state->filter);
+ }
+
+ /* Be tidy: */
+ MemoryContextDelete(state->targetcontext);
+}
+
+/*
+ * Given a left-most block at some level, move right, verifying each page
+ * individually (with more verification across pages for "readonly"
+ * callers). Caller should pass the true root page as the leftmost initially,
+ * working their way down by passing what is returned for the last call here
+ * until level 0 (leaf page level) was reached.
+ *
+ * Returns state for next call, if any. This includes left-most block number
+ * one level lower that should be passed on next level/call, which is set to
+ * P_NONE on last call here (when leaf level is verified). Level numbers
+ * follow the nbtree convention: higher levels have higher numbers, because new
+ * levels are added only due to a root page split. Note that prior to the
+ * first root page split, the root is also a leaf page, so there is always a
+ * level 0 (leaf level), and it's always the last level processed.
+ *
+ * Note on memory management: State's per-page context is reset here, between
+ * each call to bt_target_page_check().
+ */
+static BtreeLevel
+bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
+{
+ /* State to establish early, concerning entire level */
+ BTPageOpaque opaque;
+ MemoryContext oldcontext;
+ BtreeLevel nextleveldown;
+
+ /* Variables for iterating across level using right links */
+ BlockNumber leftcurrent = P_NONE;
+ BlockNumber current = level.leftmost;
+
+ /* Initialize return state */
+ nextleveldown.leftmost = InvalidBlockNumber;
+ nextleveldown.level = InvalidBtreeLevel;
+ nextleveldown.istruerootlevel = false;
+
+ /* Use page-level context for duration of this call */
+ oldcontext = MemoryContextSwitchTo(state->targetcontext);
+
+ elog(DEBUG1, "verifying level %u%s", level.level,
+ level.istruerootlevel ?
+ " (true root level)" : level.level == 0 ? " (leaf level)" : "");
+
+ state->prevrightlink = InvalidBlockNumber;
+ state->previncompletesplit = false;
+
+ do
+ {
+ /* Don't rely on CHECK_FOR_INTERRUPTS() calls at lower level */
+ CHECK_FOR_INTERRUPTS();
+
+ /* Initialize state for this iteration */
+ state->targetblock = current;
+ state->target = palloc_btree_page(state, state->targetblock);
+ state->targetlsn = PageGetLSN(state->target);
+
+ opaque = BTPageGetOpaque(state->target);
+
+ if (P_IGNORE(opaque))
+ {
+ /*
+ * Since there cannot be a concurrent VACUUM operation in readonly
+ * mode, and since a page has no links within other pages
+ * (siblings and parent) once it is marked fully deleted, it
+ * should be impossible to land on a fully deleted page in
+ * readonly mode. See bt_child_check() for further details.
+ *
+ * The bt_child_check() P_ISDELETED() check is repeated here so
+ * that pages that are only reachable through sibling links get
+ * checked.
+ */
+ if (state->readonly && P_ISDELETED(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("downlink or sibling link points to deleted block in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block=%u left block=%u left link from block=%u.",
+ current, leftcurrent, opaque->btpo_prev)));
+
+ if (P_RIGHTMOST(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("block %u fell off the end of index \"%s\"",
+ current, RelationGetRelationName(state->rel))));
+ else
+ ereport(DEBUG1,
+ (errcode(ERRCODE_NO_DATA),
+ errmsg_internal("block %u of index \"%s\" concurrently deleted",
+ current, RelationGetRelationName(state->rel))));
+ goto nextpage;
+ }
+ else if (nextleveldown.leftmost == InvalidBlockNumber)
+ {
+ /*
+ * A concurrent page split could make the caller supplied leftmost
+ * block no longer contain the leftmost page, or no longer be the
+ * true root, but where that isn't possible due to heavyweight
+ * locking, check that the first valid page meets caller's
+ * expectations.
+ */
+ if (state->readonly)
+ {
+ if (!bt_leftmost_ignoring_half_dead(state, current, opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("block %u is not leftmost in index \"%s\"",
+ current, RelationGetRelationName(state->rel))));
+
+ if (level.istruerootlevel && !P_ISROOT(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("block %u is not true root in index \"%s\"",
+ current, RelationGetRelationName(state->rel))));
+ }
+
+ /*
+ * Before beginning any non-trivial examination of level, prepare
+ * state for next bt_check_level_from_leftmost() invocation for
+ * the next level for the next level down (if any).
+ *
+ * There should be at least one non-ignorable page per level,
+ * unless this is the leaf level, which is assumed by caller to be
+ * final level.
+ */
+ if (!P_ISLEAF(opaque))
+ {
+ IndexTuple itup;
+ ItemId itemid;
+
+ /* Internal page -- downlink gets leftmost on next level */
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target,
+ P_FIRSTDATAKEY(opaque));
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+ nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
+ nextleveldown.level = opaque->btpo_level - 1;
+ }
+ else
+ {
+ /*
+ * Leaf page -- final level caller must process.
+ *
+ * Note that this could also be the root page, if there has
+ * been no root page split yet.
+ */
+ nextleveldown.leftmost = P_NONE;
+ nextleveldown.level = InvalidBtreeLevel;
+ }
+
+ /*
+ * Finished setting up state for this call/level. Control will
+ * never end up back here in any future loop iteration for this
+ * level.
+ */
+ }
+
+ /*
+ * Sibling links should be in mutual agreement. There arises
+ * leftcurrent == P_NONE && btpo_prev != P_NONE when the left sibling
+ * of the parent's low-key downlink is half-dead. (A half-dead page
+ * has no downlink from its parent.) Under heavyweight locking, the
+ * last bt_leftmost_ignoring_half_dead() validated this btpo_prev.
+ * Without heavyweight locking, validation of the P_NONE case remains
+ * unimplemented.
+ */
+ if (opaque->btpo_prev != leftcurrent && leftcurrent != P_NONE)
+ bt_recheck_sibling_links(state, opaque->btpo_prev, leftcurrent);
+
+ /* Check level */
+ if (level.level != opaque->btpo_level)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("leftmost down link for level points to block in index \"%s\" whose level is not one level down",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block pointed to=%u expected level=%u level in pointed to block=%u.",
+ current, level.level, opaque->btpo_level)));
+
+ /* Verify invariants for page */
+ bt_target_page_check(state);
+
+nextpage:
+
+ /* Try to detect circular links */
+ if (current == leftcurrent || current == opaque->btpo_prev)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("circular link chain found in block %u of index \"%s\"",
+ current, RelationGetRelationName(state->rel))));
+
+ leftcurrent = current;
+ current = opaque->btpo_next;
+
+ if (state->lowkey)
+ {
+ Assert(state->readonly);
+ pfree(state->lowkey);
+ state->lowkey = NULL;
+ }
+
+ /*
+ * Copy current target high key as the low key of right sibling.
+ * Allocate memory in upper level context, so it would be cleared
+ * after reset of target context.
+ *
+ * We only need the low key in corner cases of checking child high
+ * keys. We use high key only when incomplete split on the child level
+ * falls to the boundary of pages on the target level. See
+ * bt_child_highkey_check() for details. So, typically we won't end
+ * up doing anything with low key, but it's simpler for general case
+ * high key verification to always have it available.
+ *
+ * The correctness of managing low key in the case of concurrent
+ * splits wasn't investigated yet. Thankfully we only need low key
+ * for readonly verification and concurrent splits won't happen.
+ */
+ if (state->readonly && !P_RIGHTMOST(opaque))
+ {
+ IndexTuple itup;
+ ItemId itemid;
+
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target, P_HIKEY);
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+
+ state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
+ memcpy(state->lowkey, itup, IndexTupleSize(itup));
+ }
+
+ /* Free page and associated memory for this iteration */
+ MemoryContextReset(state->targetcontext);
+ }
+ while (current != P_NONE);
+
+ if (state->lowkey)
+ {
+ Assert(state->readonly);
+ pfree(state->lowkey);
+ state->lowkey = NULL;
+ }
+
+ /* Don't change context for caller */
+ MemoryContextSwitchTo(oldcontext);
+
+ return nextleveldown;
+}
+
+/*
+ * Like P_LEFTMOST(start_opaque), but accept an arbitrarily-long chain of
+ * half-dead, sibling-linked pages to the left. If a half-dead page appears
+ * under state->readonly, the database exited recovery between the first-stage
+ * and second-stage WAL records of a deletion.
+ */
+static bool
+bt_leftmost_ignoring_half_dead(BtreeCheckState *state,
+ BlockNumber start,
+ BTPageOpaque start_opaque)
+{
+ BlockNumber reached = start_opaque->btpo_prev,
+ reached_from = start;
+ bool all_half_dead = true;
+
+ /*
+ * To handle the !readonly case, we'd need to accept BTP_DELETED pages and
+ * potentially observe nbtree/README "Page deletion and backwards scans".
+ */
+ Assert(state->readonly);
+
+ while (reached != P_NONE && all_half_dead)
+ {
+ Page page = palloc_btree_page(state, reached);
+ BTPageOpaque reached_opaque = BTPageGetOpaque(page);
+
+ CHECK_FOR_INTERRUPTS();
+
+ /*
+ * Try to detect btpo_prev circular links. _bt_unlink_halfdead_page()
+ * writes that side-links will continue to point to the siblings.
+ * Check btpo_next for that property.
+ */
+ all_half_dead = P_ISHALFDEAD(reached_opaque) &&
+ reached != start &&
+ reached != reached_from &&
+ reached_opaque->btpo_next == reached_from;
+ if (all_half_dead)
+ {
+ XLogRecPtr pagelsn = PageGetLSN(page);
+
+ /* pagelsn should point to an XLOG_BTREE_MARK_PAGE_HALFDEAD */
+ ereport(DEBUG1,
+ (errcode(ERRCODE_NO_DATA),
+ errmsg_internal("harmless interrupted page deletion detected in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block=%u right block=%u page lsn=%X/%X.",
+ reached, reached_from,
+ LSN_FORMAT_ARGS(pagelsn))));
+
+ reached_from = reached;
+ reached = reached_opaque->btpo_prev;
+ }
+
+ pfree(page);
+ }
+
+ return all_half_dead;
+}
+
+/*
+ * Raise an error when target page's left link does not point back to the
+ * previous target page, called leftcurrent here. The leftcurrent page's
+ * right link was followed to get to the current target page, and we expect
+ * mutual agreement among leftcurrent and the current target page. Make sure
+ * that this condition has definitely been violated in the !readonly case,
+ * where concurrent page splits are something that we need to deal with.
+ *
+ * Cross-page inconsistencies involving pages that don't agree about being
+ * siblings are known to be a particularly good indicator of corruption
+ * involving partial writes/lost updates. The bt_right_page_check_scankey
+ * check also provides a way of detecting cross-page inconsistencies for
+ * !readonly callers, but it can only detect sibling pages that have an
+ * out-of-order keyspace, which can't catch many of the problems that we
+ * expect to catch here.
+ *
+ * The classic example of the kind of inconsistency that we can only catch
+ * with this check (when in !readonly mode) involves three sibling pages that
+ * were affected by a faulty page split at some point in the past. The
+ * effects of the split are reflected in the original page and its new right
+ * sibling page, with a lack of any accompanying changes for the _original_
+ * right sibling page. The original right sibling page's left link fails to
+ * point to the new right sibling page (its left link still points to the
+ * original page), even though the first phase of a page split is supposed to
+ * work as a single atomic action. This subtle inconsistency will probably
+ * only break backwards scans in practice.
+ *
+ * Note that this is the only place where amcheck will "couple" buffer locks
+ * (and only for !readonly callers). In general we prefer to avoid more
+ * thorough cross-page checks in !readonly mode, but it seems worth the
+ * complexity here. Also, the performance overhead of performing lock
+ * coupling here is negligible in practice. Control only reaches here with a
+ * non-corrupt index when there is a concurrent page split at the instant
+ * caller crossed over to target page from leftcurrent page.
+ */
+static void
+bt_recheck_sibling_links(BtreeCheckState *state,
+ BlockNumber btpo_prev_from_target,
+ BlockNumber leftcurrent)
+{
+ /* passing metapage to BTPageGetOpaque() would give irrelevant findings */
+ Assert(leftcurrent != P_NONE);
+
+ if (!state->readonly)
+ {
+ Buffer lbuf;
+ Buffer newtargetbuf;
+ Page page;
+ BTPageOpaque opaque;
+ BlockNumber newtargetblock;
+
+ /* Couple locks in the usual order for nbtree: Left to right */
+ lbuf = ReadBufferExtended(state->rel, MAIN_FORKNUM, leftcurrent,
+ RBM_NORMAL, state->checkstrategy);
+ LockBuffer(lbuf, BT_READ);
+ _bt_checkpage(state->rel, lbuf);
+ page = BufferGetPage(lbuf);
+ opaque = BTPageGetOpaque(page);
+ if (P_ISDELETED(opaque))
+ {
+ /*
+ * Cannot reason about concurrently deleted page -- the left link
+ * in the page to the right is expected to point to some other
+ * page to the left (not leftcurrent page).
+ *
+ * Note that we deliberately don't give up with a half-dead page.
+ */
+ UnlockReleaseBuffer(lbuf);
+ return;
+ }
+
+ newtargetblock = opaque->btpo_next;
+ /* Avoid self-deadlock when newtargetblock == leftcurrent */
+ if (newtargetblock != leftcurrent)
+ {
+ newtargetbuf = ReadBufferExtended(state->rel, MAIN_FORKNUM,
+ newtargetblock, RBM_NORMAL,
+ state->checkstrategy);
+ LockBuffer(newtargetbuf, BT_READ);
+ _bt_checkpage(state->rel, newtargetbuf);
+ page = BufferGetPage(newtargetbuf);
+ opaque = BTPageGetOpaque(page);
+ /* btpo_prev_from_target may have changed; update it */
+ btpo_prev_from_target = opaque->btpo_prev;
+ }
+ else
+ {
+ /*
+ * leftcurrent right sibling points back to leftcurrent block.
+ * Index is corrupt. Easiest way to handle this is to pretend
+ * that we actually read from a distinct page that has an invalid
+ * block number in its btpo_prev.
+ */
+ newtargetbuf = InvalidBuffer;
+ btpo_prev_from_target = InvalidBlockNumber;
+ }
+
+ /*
+ * No need to check P_ISDELETED here, since new target block cannot be
+ * marked deleted as long as we hold a lock on lbuf
+ */
+ if (BufferIsValid(newtargetbuf))
+ UnlockReleaseBuffer(newtargetbuf);
+ UnlockReleaseBuffer(lbuf);
+
+ if (btpo_prev_from_target == leftcurrent)
+ {
+ /* Report split in left sibling, not target (or new target) */
+ ereport(DEBUG1,
+ (errcode(ERRCODE_INTERNAL_ERROR),
+ errmsg_internal("harmless concurrent page split detected in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block=%u new right sibling=%u original right sibling=%u.",
+ leftcurrent, newtargetblock,
+ state->targetblock)));
+ return;
+ }
+
+ /*
+ * Index is corrupt. Make sure that we report correct target page.
+ *
+ * This could have changed in cases where there was a concurrent page
+ * split, as well as index corruption (at least in theory). Note that
+ * btpo_prev_from_target was already updated above.
+ */
+ state->targetblock = newtargetblock;
+ }
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("left link/right link pair in index \"%s\" not in agreement",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block=%u left block=%u left link from block=%u.",
+ state->targetblock, leftcurrent,
+ btpo_prev_from_target)));
+}
+
+/*
+ * Function performs the following checks on target page, or pages ancillary to
+ * target page:
+ *
+ * - That every "real" data item is less than or equal to the high key, which
+ * is an upper bound on the items on the page. Data items should be
+ * strictly less than the high key when the page is an internal page.
+ *
+ * - That within the page, every data item is strictly less than the item
+ * immediately to its right, if any (i.e., that the items are in order
+ * within the page, so that the binary searches performed by index scans are
+ * sane).
+ *
+ * - That the last data item stored on the page is strictly less than the
+ * first data item on the page to the right (when such a first item is
+ * available).
+ *
+ * - Various checks on the structure of tuples themselves. For example, check
+ * that non-pivot tuples have no truncated attributes.
+ *
+ * Furthermore, when state passed shows ShareLock held, function also checks:
+ *
+ * - That all child pages respect strict lower bound from parent's pivot
+ * tuple.
+ *
+ * - That downlink to block was encountered in parent where that's expected.
+ *
+ * - That high keys of child pages matches corresponding pivot keys in parent.
+ *
+ * This is also where heapallindexed callers use their Bloom filter to
+ * fingerprint IndexTuples for later table_index_build_scan() verification.
+ *
+ * Note: Memory allocated in this routine is expected to be released by caller
+ * resetting state->targetcontext.
+ */
+static void
+bt_target_page_check(BtreeCheckState *state)
+{
+ OffsetNumber offset;
+ OffsetNumber max;
+ BTPageOpaque topaque;
+
+ topaque = BTPageGetOpaque(state->target);
+ max = PageGetMaxOffsetNumber(state->target);
+
+ elog(DEBUG2, "verifying %u items on %s block %u", max,
+ P_ISLEAF(topaque) ? "leaf" : "internal", state->targetblock);
+
+ /*
+ * Check the number of attributes in high key. Note, rightmost page
+ * doesn't contain a high key, so nothing to check
+ */
+ if (!P_RIGHTMOST(topaque))
+ {
+ ItemId itemid;
+ IndexTuple itup;
+
+ /* Verify line pointer before checking tuple */
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target, P_HIKEY);
+ if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
+ P_HIKEY))
+ {
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("wrong number of high key index tuple attributes in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index block=%u natts=%u block type=%s page lsn=%X/%X.",
+ state->targetblock,
+ BTreeTupleGetNAtts(itup, state->rel),
+ P_ISLEAF(topaque) ? "heap" : "index",
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+ }
+
+ /*
+ * Loop over page items, starting from first non-highkey item, not high
+ * key (if any). Most tests are not performed for the "negative infinity"
+ * real item (if any).
+ */
+ for (offset = P_FIRSTDATAKEY(topaque);
+ offset <= max;
+ offset = OffsetNumberNext(offset))
+ {
+ ItemId itemid;
+ IndexTuple itup;
+ size_t tupsize;
+ BTScanInsert skey;
+ bool lowersizelimit;
+ ItemPointer scantid;
+
+ CHECK_FOR_INTERRUPTS();
+
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target, offset);
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+ tupsize = IndexTupleSize(itup);
+
+ /*
+ * lp_len should match the IndexTuple reported length exactly, since
+ * lp_len is completely redundant in indexes, and both sources of
+ * tuple length are MAXALIGN()'d. nbtree does not use lp_len all that
+ * frequently, and is surprisingly tolerant of corrupt lp_len fields.
+ */
+ if (tupsize != ItemIdGetLength(itemid))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index tuple size does not equal lp_len in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=(%u,%u) tuple size=%zu lp_len=%u page lsn=%X/%X.",
+ state->targetblock, offset,
+ tupsize, ItemIdGetLength(itemid),
+ LSN_FORMAT_ARGS(state->targetlsn)),
+ errhint("This could be a torn page problem.")));
+
+ /* Check the number of index tuple attributes */
+ if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
+ offset))
+ {
+ ItemPointer tid;
+ char *itid,
+ *htid;
+
+ itid = psprintf("(%u,%u)", state->targetblock, offset);
+ tid = BTreeTupleGetPointsToTID(itup);
+ htid = psprintf("(%u,%u)",
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("wrong number of index tuple attributes in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=%s natts=%u points to %s tid=%s page lsn=%X/%X.",
+ itid,
+ BTreeTupleGetNAtts(itup, state->rel),
+ P_ISLEAF(topaque) ? "heap" : "index",
+ htid,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+
+ /*
+ * Don't try to generate scankey using "negative infinity" item on
+ * internal pages. They are always truncated to zero attributes.
+ */
+ if (offset_is_negative_infinity(topaque, offset))
+ {
+ /*
+ * We don't call bt_child_check() for "negative infinity" items.
+ * But if we're performing downlink connectivity check, we do it
+ * for every item including "negative infinity" one.
+ */
+ if (!P_ISLEAF(topaque) && state->readonly)
+ {
+ bt_child_highkey_check(state,
+ offset,
+ NULL,
+ topaque->btpo_level);
+ }
+ continue;
+ }
+
+ /*
+ * Readonly callers may optionally verify that non-pivot tuples can
+ * each be found by an independent search that starts from the root.
+ * Note that we deliberately don't do individual searches for each
+ * TID, since the posting list itself is validated by other checks.
+ */
+ if (state->rootdescend && P_ISLEAF(topaque) &&
+ !bt_rootdescend(state, itup))
+ {
+ ItemPointer tid = BTreeTupleGetPointsToTID(itup);
+ char *itid,
+ *htid;
+
+ itid = psprintf("(%u,%u)", state->targetblock, offset);
+ htid = psprintf("(%u,%u)", ItemPointerGetBlockNumber(tid),
+ ItemPointerGetOffsetNumber(tid));
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("could not find tuple using search from root page in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=%s points to heap tid=%s page lsn=%X/%X.",
+ itid, htid,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+
+ /*
+ * If tuple is a posting list tuple, make sure posting list TIDs are
+ * in order
+ */
+ if (BTreeTupleIsPosting(itup))
+ {
+ ItemPointerData last;
+ ItemPointer current;
+
+ ItemPointerCopy(BTreeTupleGetHeapTID(itup), &last);
+
+ for (int i = 1; i < BTreeTupleGetNPosting(itup); i++)
+ {
+
+ current = BTreeTupleGetPostingN(itup, i);
+
+ if (ItemPointerCompare(current, &last) <= 0)
+ {
+ char *itid = psprintf("(%u,%u)", state->targetblock, offset);
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("posting list contains misplaced TID in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=%s posting list offset=%d page lsn=%X/%X.",
+ itid, i,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+
+ ItemPointerCopy(current, &last);
+ }
+ }
+
+ /* Build insertion scankey for current page offset */
+ skey = bt_mkscankey_pivotsearch(state->rel, itup);
+
+ /*
+ * Make sure tuple size does not exceed the relevant BTREE_VERSION
+ * specific limit.
+ *
+ * BTREE_VERSION 4 (which introduced heapkeyspace rules) requisitioned
+ * a small amount of space from BTMaxItemSize() in order to ensure
+ * that suffix truncation always has enough space to add an explicit
+ * heap TID back to a tuple -- we pessimistically assume that every
+ * newly inserted tuple will eventually need to have a heap TID
+ * appended during a future leaf page split, when the tuple becomes
+ * the basis of the new high key (pivot tuple) for the leaf page.
+ *
+ * Since the reclaimed space is reserved for that purpose, we must not
+ * enforce the slightly lower limit when the extra space has been used
+ * as intended. In other words, there is only a cross-version
+ * difference in the limit on tuple size within leaf pages.
+ *
+ * Still, we're particular about the details within BTREE_VERSION 4
+ * internal pages. Pivot tuples may only use the extra space for its
+ * designated purpose. Enforce the lower limit for pivot tuples when
+ * an explicit heap TID isn't actually present. (In all other cases
+ * suffix truncation is guaranteed to generate a pivot tuple that's no
+ * larger than the firstright tuple provided to it by its caller.)
+ */
+ lowersizelimit = skey->heapkeyspace &&
+ (P_ISLEAF(topaque) || BTreeTupleGetHeapTID(itup) == NULL);
+ if (tupsize > (lowersizelimit ? BTMaxItemSize(state->target) :
+ BTMaxItemSizeNoHeapTid(state->target)))
+ {
+ ItemPointer tid = BTreeTupleGetPointsToTID(itup);
+ char *itid,
+ *htid;
+
+ itid = psprintf("(%u,%u)", state->targetblock, offset);
+ htid = psprintf("(%u,%u)",
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index row size %zu exceeds maximum for index \"%s\"",
+ tupsize, RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=%s points to %s tid=%s page lsn=%X/%X.",
+ itid,
+ P_ISLEAF(topaque) ? "heap" : "index",
+ htid,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+
+ /* Fingerprint leaf page tuples (those that point to the heap) */
+ if (state->heapallindexed && P_ISLEAF(topaque) && !ItemIdIsDead(itemid))
+ {
+ IndexTuple norm;
+
+ if (BTreeTupleIsPosting(itup))
+ {
+ /* Fingerprint all elements as distinct "plain" tuples */
+ for (int i = 0; i < BTreeTupleGetNPosting(itup); i++)
+ {
+ IndexTuple logtuple;
+
+ logtuple = bt_posting_plain_tuple(itup, i);
+ norm = bt_normalize_tuple(state, logtuple);
+ bloom_add_element(state->filter, (unsigned char *) norm,
+ IndexTupleSize(norm));
+ /* Be tidy */
+ if (norm != logtuple)
+ pfree(norm);
+ pfree(logtuple);
+ }
+ }
+ else
+ {
+ norm = bt_normalize_tuple(state, itup);
+ bloom_add_element(state->filter, (unsigned char *) norm,
+ IndexTupleSize(norm));
+ /* Be tidy */
+ if (norm != itup)
+ pfree(norm);
+ }
+ }
+
+ /*
+ * * High key check *
+ *
+ * If there is a high key (if this is not the rightmost page on its
+ * entire level), check that high key actually is upper bound on all
+ * page items. If this is a posting list tuple, we'll need to set
+ * scantid to be highest TID in posting list.
+ *
+ * We prefer to check all items against high key rather than checking
+ * just the last and trusting that the operator class obeys the
+ * transitive law (which implies that all previous items also
+ * respected the high key invariant if they pass the item order
+ * check).
+ *
+ * Ideally, we'd compare every item in the index against every other
+ * item in the index, and not trust opclass obedience of the
+ * transitive law to bridge the gap between children and their
+ * grandparents (as well as great-grandparents, and so on). We don't
+ * go to those lengths because that would be prohibitively expensive,
+ * and probably not markedly more effective in practice.
+ *
+ * On the leaf level, we check that the key is <= the highkey.
+ * However, on non-leaf levels we check that the key is < the highkey,
+ * because the high key is "just another separator" rather than a copy
+ * of some existing key item; we expect it to be unique among all keys
+ * on the same level. (Suffix truncation will sometimes produce a
+ * leaf highkey that is an untruncated copy of the lastleft item, but
+ * never any other item, which necessitates weakening the leaf level
+ * check to <=.)
+ *
+ * Full explanation for why a highkey is never truly a copy of another
+ * item from the same level on internal levels:
+ *
+ * While the new left page's high key is copied from the first offset
+ * on the right page during an internal page split, that's not the
+ * full story. In effect, internal pages are split in the middle of
+ * the firstright tuple, not between the would-be lastleft and
+ * firstright tuples: the firstright key ends up on the left side as
+ * left's new highkey, and the firstright downlink ends up on the
+ * right side as right's new "negative infinity" item. The negative
+ * infinity tuple is truncated to zero attributes, so we're only left
+ * with the downlink. In other words, the copying is just an
+ * implementation detail of splitting in the middle of a (pivot)
+ * tuple. (See also: "Notes About Data Representation" in the nbtree
+ * README.)
+ */
+ scantid = skey->scantid;
+ if (state->heapkeyspace && BTreeTupleIsPosting(itup))
+ skey->scantid = BTreeTupleGetMaxHeapTID(itup);
+
+ if (!P_RIGHTMOST(topaque) &&
+ !(P_ISLEAF(topaque) ? invariant_leq_offset(state, skey, P_HIKEY) :
+ invariant_l_offset(state, skey, P_HIKEY)))
+ {
+ ItemPointer tid = BTreeTupleGetPointsToTID(itup);
+ char *itid,
+ *htid;
+
+ itid = psprintf("(%u,%u)", state->targetblock, offset);
+ htid = psprintf("(%u,%u)",
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("high key invariant violated for index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=%s points to %s tid=%s page lsn=%X/%X.",
+ itid,
+ P_ISLEAF(topaque) ? "heap" : "index",
+ htid,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+ /* Reset, in case scantid was set to (itup) posting tuple's max TID */
+ skey->scantid = scantid;
+
+ /*
+ * * Item order check *
+ *
+ * Check that items are stored on page in logical order, by checking
+ * current item is strictly less than next item (if any).
+ */
+ if (OffsetNumberNext(offset) <= max &&
+ !invariant_l_offset(state, skey, OffsetNumberNext(offset)))
+ {
+ ItemPointer tid;
+ char *itid,
+ *htid,
+ *nitid,
+ *nhtid;
+
+ itid = psprintf("(%u,%u)", state->targetblock, offset);
+ tid = BTreeTupleGetPointsToTID(itup);
+ htid = psprintf("(%u,%u)",
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
+ nitid = psprintf("(%u,%u)", state->targetblock,
+ OffsetNumberNext(offset));
+
+ /* Reuse itup to get pointed-to heap location of second item */
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target,
+ OffsetNumberNext(offset));
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+ tid = BTreeTupleGetPointsToTID(itup);
+ nhtid = psprintf("(%u,%u)",
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("item order invariant violated for index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Lower index tid=%s (points to %s tid=%s) "
+ "higher index tid=%s (points to %s tid=%s) "
+ "page lsn=%X/%X.",
+ itid,
+ P_ISLEAF(topaque) ? "heap" : "index",
+ htid,
+ nitid,
+ P_ISLEAF(topaque) ? "heap" : "index",
+ nhtid,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+
+ /*
+ * * Last item check *
+ *
+ * Check last item against next/right page's first data item's when
+ * last item on page is reached. This additional check will detect
+ * transposed pages iff the supposed right sibling page happens to
+ * belong before target in the key space. (Otherwise, a subsequent
+ * heap verification will probably detect the problem.)
+ *
+ * This check is similar to the item order check that will have
+ * already been performed for every other "real" item on target page
+ * when last item is checked. The difference is that the next item
+ * (the item that is compared to target's last item) needs to come
+ * from the next/sibling page. There may not be such an item
+ * available from sibling for various reasons, though (e.g., target is
+ * the rightmost page on level).
+ */
+ else if (offset == max)
+ {
+ BTScanInsert rightkey;
+
+ /* Get item in next/right page */
+ rightkey = bt_right_page_check_scankey(state);
+
+ if (rightkey &&
+ !invariant_g_offset(state, rightkey, max))
+ {
+ /*
+ * As explained at length in bt_right_page_check_scankey(),
+ * there is a known !readonly race that could account for
+ * apparent violation of invariant, which we must check for
+ * before actually proceeding with raising error. Our canary
+ * condition is that target page was deleted.
+ */
+ if (!state->readonly)
+ {
+ /* Get fresh copy of target page */
+ state->target = palloc_btree_page(state, state->targetblock);
+ /* Note that we deliberately do not update target LSN */
+ topaque = BTPageGetOpaque(state->target);
+
+ /*
+ * All !readonly checks now performed; just return
+ */
+ if (P_IGNORE(topaque))
+ return;
+ }
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("cross page item order invariant violated for index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Last item on page tid=(%u,%u) page lsn=%X/%X.",
+ state->targetblock, offset,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+ }
+
+ /*
+ * * Downlink check *
+ *
+ * Additional check of child items iff this is an internal page and
+ * caller holds a ShareLock. This happens for every downlink (item)
+ * in target excluding the negative-infinity downlink (again, this is
+ * because it has no useful value to compare).
+ */
+ if (!P_ISLEAF(topaque) && state->readonly)
+ bt_child_check(state, skey, offset);
+ }
+
+ /*
+ * Special case bt_child_highkey_check() call
+ *
+ * We don't pass a real downlink, but we've to finish the level
+ * processing. If condition is satisfied, we've already processed all the
+ * downlinks from the target level. But there still might be pages to the
+ * right of the child page pointer to by our rightmost downlink. And they
+ * might have missing downlinks. This final call checks for them.
+ */
+ if (!P_ISLEAF(topaque) && P_RIGHTMOST(topaque) && state->readonly)
+ {
+ bt_child_highkey_check(state, InvalidOffsetNumber,
+ NULL, topaque->btpo_level);
+ }
+}
+
+/*
+ * Return a scankey for an item on page to right of current target (or the
+ * first non-ignorable page), sufficient to check ordering invariant on last
+ * item in current target page. Returned scankey relies on local memory
+ * allocated for the child page, which caller cannot pfree(). Caller's memory
+ * context should be reset between calls here.
+ *
+ * This is the first data item, and so all adjacent items are checked against
+ * their immediate sibling item (which may be on a sibling page, or even a
+ * "cousin" page at parent boundaries where target's rightlink points to page
+ * with different parent page). If no such valid item is available, return
+ * NULL instead.
+ *
+ * Note that !readonly callers must reverify that target page has not
+ * been concurrently deleted.
+ */
+static BTScanInsert
+bt_right_page_check_scankey(BtreeCheckState *state)
+{
+ BTPageOpaque opaque;
+ ItemId rightitem;
+ IndexTuple firstitup;
+ BlockNumber targetnext;
+ Page rightpage;
+ OffsetNumber nline;
+
+ /* Determine target's next block number */
+ opaque = BTPageGetOpaque(state->target);
+
+ /* If target is already rightmost, no right sibling; nothing to do here */
+ if (P_RIGHTMOST(opaque))
+ return NULL;
+
+ /*
+ * General notes on concurrent page splits and page deletion:
+ *
+ * Routines like _bt_search() don't require *any* page split interlock
+ * when descending the tree, including something very light like a buffer
+ * pin. That's why it's okay that we don't either. This avoidance of any
+ * need to "couple" buffer locks is the raison d' etre of the Lehman & Yao
+ * algorithm, in fact.
+ *
+ * That leaves deletion. A deleted page won't actually be recycled by
+ * VACUUM early enough for us to fail to at least follow its right link
+ * (or left link, or downlink) and find its sibling, because recycling
+ * does not occur until no possible index scan could land on the page.
+ * Index scans can follow links with nothing more than their snapshot as
+ * an interlock and be sure of at least that much. (See page
+ * recycling/"visible to everyone" notes in nbtree README.)
+ *
+ * Furthermore, it's okay if we follow a rightlink and find a half-dead or
+ * dead (ignorable) page one or more times. There will either be a
+ * further right link to follow that leads to a live page before too long
+ * (before passing by parent's rightmost child), or we will find the end
+ * of the entire level instead (possible when parent page is itself the
+ * rightmost on its level).
+ */
+ targetnext = opaque->btpo_next;
+ for (;;)
+ {
+ CHECK_FOR_INTERRUPTS();
+
+ rightpage = palloc_btree_page(state, targetnext);
+ opaque = BTPageGetOpaque(rightpage);
+
+ if (!P_IGNORE(opaque) || P_RIGHTMOST(opaque))
+ break;
+
+ /*
+ * We landed on a deleted or half-dead sibling page. Step right until
+ * we locate a live sibling page.
+ */
+ ereport(DEBUG2,
+ (errcode(ERRCODE_NO_DATA),
+ errmsg_internal("level %u sibling page in block %u of index \"%s\" was found deleted or half dead",
+ opaque->btpo_level, targetnext, RelationGetRelationName(state->rel)),
+ errdetail_internal("Deleted page found when building scankey from right sibling.")));
+
+ targetnext = opaque->btpo_next;
+
+ /* Be slightly more pro-active in freeing this memory, just in case */
+ pfree(rightpage);
+ }
+
+ /*
+ * No ShareLock held case -- why it's safe to proceed.
+ *
+ * Problem:
+ *
+ * We must avoid false positive reports of corruption when caller treats
+ * item returned here as an upper bound on target's last item. In
+ * general, false positives are disallowed. Avoiding them here when
+ * caller is !readonly is subtle.
+ *
+ * A concurrent page deletion by VACUUM of the target page can result in
+ * the insertion of items on to this right sibling page that would
+ * previously have been inserted on our target page. There might have
+ * been insertions that followed the target's downlink after it was made
+ * to point to right sibling instead of target by page deletion's first
+ * phase. The inserters insert items that would belong on target page.
+ * This race is very tight, but it's possible. This is our only problem.
+ *
+ * Non-problems:
+ *
+ * We are not hindered by a concurrent page split of the target; we'll
+ * never land on the second half of the page anyway. A concurrent split
+ * of the right page will also not matter, because the first data item
+ * remains the same within the left half, which we'll reliably land on. If
+ * we had to skip over ignorable/deleted pages, it cannot matter because
+ * their key space has already been atomically merged with the first
+ * non-ignorable page we eventually find (doesn't matter whether the page
+ * we eventually find is a true sibling or a cousin of target, which we go
+ * into below).
+ *
+ * Solution:
+ *
+ * Caller knows that it should reverify that target is not ignorable
+ * (half-dead or deleted) when cross-page sibling item comparison appears
+ * to indicate corruption (invariant fails). This detects the single race
+ * condition that exists for caller. This is correct because the
+ * continued existence of target block as non-ignorable (not half-dead or
+ * deleted) implies that target page was not merged into from the right by
+ * deletion; the key space at or after target never moved left. Target's
+ * parent either has the same downlink to target as before, or a <
+ * downlink due to deletion at the left of target. Target either has the
+ * same highkey as before, or a highkey < before when there is a page
+ * split. (The rightmost concurrently-split-from-target-page page will
+ * still have the same highkey as target was originally found to have,
+ * which for our purposes is equivalent to target's highkey itself never
+ * changing, since we reliably skip over
+ * concurrently-split-from-target-page pages.)
+ *
+ * In simpler terms, we allow that the key space of the target may expand
+ * left (the key space can move left on the left side of target only), but
+ * the target key space cannot expand right and get ahead of us without
+ * our detecting it. The key space of the target cannot shrink, unless it
+ * shrinks to zero due to the deletion of the original page, our canary
+ * condition. (To be very precise, we're a bit stricter than that because
+ * it might just have been that the target page split and only the
+ * original target page was deleted. We can be more strict, just not more
+ * lax.)
+ *
+ * Top level tree walk caller moves on to next page (makes it the new
+ * target) following recovery from this race. (cf. The rationale for
+ * child/downlink verification needing a ShareLock within
+ * bt_child_check(), where page deletion is also the main source of
+ * trouble.)
+ *
+ * Note that it doesn't matter if right sibling page here is actually a
+ * cousin page, because in order for the key space to be readjusted in a
+ * way that causes us issues in next level up (guiding problematic
+ * concurrent insertions to the cousin from the grandparent rather than to
+ * the sibling from the parent), there'd have to be page deletion of
+ * target's parent page (affecting target's parent's downlink in target's
+ * grandparent page). Internal page deletion only occurs when there are
+ * no child pages (they were all fully deleted), and caller is checking
+ * that the target's parent has at least one non-deleted (so
+ * non-ignorable) child: the target page. (Note that the first phase of
+ * deletion atomically marks the page to be deleted half-dead/ignorable at
+ * the same time downlink in its parent is removed, so caller will
+ * definitely not fail to detect that this happened.)
+ *
+ * This trick is inspired by the method backward scans use for dealing
+ * with concurrent page splits; concurrent page deletion is a problem that
+ * similarly receives special consideration sometimes (it's possible that
+ * the backwards scan will re-read its "original" block after failing to
+ * find a right-link to it, having already moved in the opposite direction
+ * (right/"forwards") a few times to try to locate one). Just like us,
+ * that happens only to determine if there was a concurrent page deletion
+ * of a reference page, and just like us if there was a page deletion of
+ * that reference page it means we can move on from caring about the
+ * reference page. See the nbtree README for a full description of how
+ * that works.
+ */
+ nline = PageGetMaxOffsetNumber(rightpage);
+
+ /*
+ * Get first data item, if any
+ */
+ if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
+ {
+ /* Return first data item (if any) */
+ rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
+ P_FIRSTDATAKEY(opaque));
+ }
+ else if (!P_ISLEAF(opaque) &&
+ nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
+ {
+ /*
+ * Return first item after the internal page's "negative infinity"
+ * item
+ */
+ rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
+ OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+ }
+ else
+ {
+ /*
+ * No first item. Page is probably empty leaf page, but it's also
+ * possible that it's an internal page with only a negative infinity
+ * item.
+ */
+ ereport(DEBUG2,
+ (errcode(ERRCODE_NO_DATA),
+ errmsg_internal("%s block %u of index \"%s\" has no first data item",
+ P_ISLEAF(opaque) ? "leaf" : "internal", targetnext,
+ RelationGetRelationName(state->rel))));
+ return NULL;
+ }
+
+ /*
+ * Return first real item scankey. Note that this relies on right page
+ * memory remaining allocated.
+ */
+ firstitup = (IndexTuple) PageGetItem(rightpage, rightitem);
+ return bt_mkscankey_pivotsearch(state->rel, firstitup);
+}
+
+/*
+ * Check if two tuples are binary identical except the block number. So,
+ * this function is capable to compare pivot keys on different levels.
+ */
+static bool
+bt_pivot_tuple_identical(bool heapkeyspace, IndexTuple itup1, IndexTuple itup2)
+{
+ if (IndexTupleSize(itup1) != IndexTupleSize(itup2))
+ return false;
+
+ if (heapkeyspace)
+ {
+ /*
+ * Offset number will contain important information in heapkeyspace
+ * indexes: the number of attributes left in the pivot tuple following
+ * suffix truncation. Don't skip over it (compare it too).
+ */
+ if (memcmp(&itup1->t_tid.ip_posid, &itup2->t_tid.ip_posid,
+ IndexTupleSize(itup1) -
+ offsetof(ItemPointerData, ip_posid)) != 0)
+ return false;
+ }
+ else
+ {
+ /*
+ * Cannot rely on offset number field having consistent value across
+ * levels on pg_upgrade'd !heapkeyspace indexes. Compare contents of
+ * tuple starting from just after item pointer (i.e. after block
+ * number and offset number).
+ */
+ if (memcmp(&itup1->t_info, &itup2->t_info,
+ IndexTupleSize(itup1) -
+ offsetof(IndexTupleData, t_info)) != 0)
+ return false;
+ }
+
+ return true;
+}
+
+/*---
+ * Check high keys on the child level. Traverse rightlinks from previous
+ * downlink to the current one. Check that there are no intermediate pages
+ * with missing downlinks.
+ *
+ * If 'loaded_child' is given, it's assumed to be the page pointed to by the
+ * downlink referenced by 'downlinkoffnum' of the target page.
+ *
+ * Basically this function is called for each target downlink and checks two
+ * invariants:
+ *
+ * 1) You can reach the next child from previous one via rightlinks;
+ * 2) Each child high key have matching pivot key on target level.
+ *
+ * Consider the sample tree picture.
+ *
+ * 1
+ * / \
+ * 2 <-> 3
+ * / \ / \
+ * 4 <> 5 <> 6 <> 7 <> 8
+ *
+ * This function will be called for blocks 4, 5, 6 and 8. Consider what is
+ * happening for each function call.
+ *
+ * - The function call for block 4 initializes data structure and matches high
+ * key of block 4 to downlink's pivot key of block 2.
+ * - The high key of block 5 is matched to the high key of block 2.
+ * - The block 6 has an incomplete split flag set, so its high key isn't
+ * matched to anything.
+ * - The function call for block 8 checks that block 8 can be found while
+ * following rightlinks from block 6. The high key of block 7 will be
+ * matched to downlink's pivot key in block 3.
+ *
+ * There is also final call of this function, which checks that there is no
+ * missing downlinks for children to the right of the child referenced by
+ * rightmost downlink in target level.
+ */
+static void
+bt_child_highkey_check(BtreeCheckState *state,
+ OffsetNumber target_downlinkoffnum,
+ Page loaded_child,
+ uint32 target_level)
+{
+ BlockNumber blkno = state->prevrightlink;
+ Page page;
+ BTPageOpaque opaque;
+ bool rightsplit = state->previncompletesplit;
+ bool first = true;
+ ItemId itemid;
+ IndexTuple itup;
+ BlockNumber downlink;
+
+ if (OffsetNumberIsValid(target_downlinkoffnum))
+ {
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target, target_downlinkoffnum);
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+ downlink = BTreeTupleGetDownLink(itup);
+ }
+ else
+ {
+ downlink = P_NONE;
+ }
+
+ /*
+ * If no previous rightlink is memorized for current level just below
+ * target page's level, we are about to start from the leftmost page. We
+ * can't follow rightlinks from previous page, because there is no
+ * previous page. But we still can match high key.
+ *
+ * So we initialize variables for the loop above like there is previous
+ * page referencing current child. Also we imply previous page to not
+ * have incomplete split flag, that would make us require downlink for
+ * current child. That's correct, because leftmost page on the level
+ * should always have parent downlink.
+ */
+ if (!BlockNumberIsValid(blkno))
+ {
+ blkno = downlink;
+ rightsplit = false;
+ }
+
+ /* Move to the right on the child level */
+ while (true)
+ {
+ /*
+ * Did we traverse the whole tree level and this is check for pages to
+ * the right of rightmost downlink?
+ */
+ if (blkno == P_NONE && downlink == P_NONE)
+ {
+ state->prevrightlink = InvalidBlockNumber;
+ state->previncompletesplit = false;
+ return;
+ }
+
+ /* Did we traverse the whole tree level and don't find next downlink? */
+ if (blkno == P_NONE)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("can't traverse from downlink %u to downlink %u of index \"%s\"",
+ state->prevrightlink, downlink,
+ RelationGetRelationName(state->rel))));
+
+ /* Load page contents */
+ if (blkno == downlink && loaded_child)
+ page = loaded_child;
+ else
+ page = palloc_btree_page(state, blkno);
+
+ opaque = BTPageGetOpaque(page);
+
+ /* The first page we visit at the level should be leftmost */
+ if (first && !BlockNumberIsValid(state->prevrightlink) &&
+ !bt_leftmost_ignoring_half_dead(state, blkno, opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("the first child of leftmost target page is not leftmost of its level in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Target block=%u child block=%u target page lsn=%X/%X.",
+ state->targetblock, blkno,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+
+ /* Do level sanity check */
+ if ((!P_ISDELETED(opaque) || P_HAS_FULLXID(opaque)) &&
+ opaque->btpo_level != target_level - 1)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("block found while following rightlinks from child of index \"%s\" has invalid level",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block pointed to=%u expected level=%u level in pointed to block=%u.",
+ blkno, target_level - 1, opaque->btpo_level)));
+
+ /* Try to detect circular links */
+ if ((!first && blkno == state->prevrightlink) || blkno == opaque->btpo_prev)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("circular link chain found in block %u of index \"%s\"",
+ blkno, RelationGetRelationName(state->rel))));
+
+ if (blkno != downlink && !P_IGNORE(opaque))
+ {
+ /* blkno probably has missing parent downlink */
+ bt_downlink_missing_check(state, rightsplit, blkno, page);
+ }
+
+ rightsplit = P_INCOMPLETE_SPLIT(opaque);
+
+ /*
+ * If we visit page with high key, check that it is equal to the
+ * target key next to corresponding downlink.
+ */
+ if (!rightsplit && !P_RIGHTMOST(opaque))
+ {
+ BTPageOpaque topaque;
+ IndexTuple highkey;
+ OffsetNumber pivotkey_offset;
+
+ /* Get high key */
+ itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+ highkey = (IndexTuple) PageGetItem(page, itemid);
+
+ /*
+ * There might be two situations when we examine high key. If
+ * current child page is referenced by given target downlink, we
+ * should look to the next offset number for matching key from
+ * target page.
+ *
+ * Alternatively, we're following rightlinks somewhere in the
+ * middle between page referenced by previous target's downlink
+ * and the page referenced by current target's downlink. If
+ * current child page hasn't incomplete split flag set, then its
+ * high key should match to the target's key of current offset
+ * number. This happens when a previous call here (to
+ * bt_child_highkey_check()) found an incomplete split, and we
+ * reach a right sibling page without a downlink -- the right
+ * sibling page's high key still needs to be matched to a
+ * separator key on the parent/target level.
+ *
+ * Don't apply OffsetNumberNext() to target_downlinkoffnum when we
+ * already had to step right on the child level. Our traversal of
+ * the child level must try to move in perfect lockstep behind (to
+ * the left of) the target/parent level traversal.
+ */
+ if (blkno == downlink)
+ pivotkey_offset = OffsetNumberNext(target_downlinkoffnum);
+ else
+ pivotkey_offset = target_downlinkoffnum;
+
+ topaque = BTPageGetOpaque(state->target);
+
+ if (!offset_is_negative_infinity(topaque, pivotkey_offset))
+ {
+ /*
+ * If we're looking for the next pivot tuple in target page,
+ * but there is no more pivot tuples, then we should match to
+ * high key instead.
+ */
+ if (pivotkey_offset > PageGetMaxOffsetNumber(state->target))
+ {
+ if (P_RIGHTMOST(topaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("child high key is greater than rightmost pivot key on target level in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Target block=%u child block=%u target page lsn=%X/%X.",
+ state->targetblock, blkno,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ pivotkey_offset = P_HIKEY;
+ }
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target, pivotkey_offset);
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+ }
+ else
+ {
+ /*
+ * We cannot try to match child's high key to a negative
+ * infinity key in target, since there is nothing to compare.
+ * However, it's still possible to match child's high key
+ * outside of target page. The reason why we're are is that
+ * bt_child_highkey_check() was previously called for the
+ * cousin page of 'loaded_child', which is incomplete split.
+ * So, now we traverse to the right of that cousin page and
+ * current child level page under consideration still belongs
+ * to the subtree of target's left sibling. Thus, we need to
+ * match child's high key to it's left uncle page high key.
+ * Thankfully we saved it, it's called a "low key" of target
+ * page.
+ */
+ if (!state->lowkey)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("can't find left sibling high key in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Target block=%u child block=%u target page lsn=%X/%X.",
+ state->targetblock, blkno,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ itup = state->lowkey;
+ }
+
+ if (!bt_pivot_tuple_identical(state->heapkeyspace, highkey, itup))
+ {
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("mismatch between parent key and child high key in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Target block=%u child block=%u target page lsn=%X/%X.",
+ state->targetblock, blkno,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+ }
+
+ /* Exit if we already found next downlink */
+ if (blkno == downlink)
+ {
+ state->prevrightlink = opaque->btpo_next;
+ state->previncompletesplit = rightsplit;
+ return;
+ }
+
+ /* Traverse to the next page using rightlink */
+ blkno = opaque->btpo_next;
+
+ /* Free page contents if it's allocated by us */
+ if (page != loaded_child)
+ pfree(page);
+ first = false;
+ }
+}
+
+/*
+ * Checks one of target's downlink against its child page.
+ *
+ * Conceptually, the target page continues to be what is checked here. The
+ * target block is still blamed in the event of finding an invariant violation.
+ * The downlink insertion into the target is probably where any problem raised
+ * here arises, and there is no such thing as a parent link, so doing the
+ * verification this way around is much more practical.
+ *
+ * This function visits child page and it's sequentially called for each
+ * downlink of target page. Assuming this we also check downlink connectivity
+ * here in order to save child page visits.
+ */
+static void
+bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
+ OffsetNumber downlinkoffnum)
+{
+ ItemId itemid;
+ IndexTuple itup;
+ BlockNumber childblock;
+ OffsetNumber offset;
+ OffsetNumber maxoffset;
+ Page child;
+ BTPageOpaque copaque;
+ BTPageOpaque topaque;
+
+ itemid = PageGetItemIdCareful(state, state->targetblock,
+ state->target, downlinkoffnum);
+ itup = (IndexTuple) PageGetItem(state->target, itemid);
+ childblock = BTreeTupleGetDownLink(itup);
+
+ /*
+ * Caller must have ShareLock on target relation, because of
+ * considerations around page deletion by VACUUM.
+ *
+ * NB: In general, page deletion deletes the right sibling's downlink, not
+ * the downlink of the page being deleted; the deleted page's downlink is
+ * reused for its sibling. The key space is thereby consolidated between
+ * the deleted page and its right sibling. (We cannot delete a parent
+ * page's rightmost child unless it is the last child page, and we intend
+ * to also delete the parent itself.)
+ *
+ * If this verification happened without a ShareLock, the following race
+ * condition could cause false positives:
+ *
+ * In general, concurrent page deletion might occur, including deletion of
+ * the left sibling of the child page that is examined here. If such a
+ * page deletion were to occur, closely followed by an insertion into the
+ * newly expanded key space of the child, a window for the false positive
+ * opens up: the stale parent/target downlink originally followed to get
+ * to the child legitimately ceases to be a lower bound on all items in
+ * the page, since the key space was concurrently expanded "left".
+ * (Insertion followed the "new" downlink for the child, not our now-stale
+ * downlink, which was concurrently physically removed in target/parent as
+ * part of deletion's first phase.)
+ *
+ * While we use various techniques elsewhere to perform cross-page
+ * verification for !readonly callers, a similar trick seems difficult
+ * here. The tricks used by bt_recheck_sibling_links and by
+ * bt_right_page_check_scankey both involve verification of a same-level,
+ * cross-sibling invariant. Cross-level invariants are far more squishy,
+ * though. The nbtree REDO routines do not actually couple buffer locks
+ * across levels during page splits, so making any cross-level check work
+ * reliably in !readonly mode may be impossible.
+ */
+ Assert(state->readonly);
+
+ /*
+ * Verify child page has the downlink key from target page (its parent) as
+ * a lower bound; downlink must be strictly less than all keys on the
+ * page.
+ *
+ * Check all items, rather than checking just the first and trusting that
+ * the operator class obeys the transitive law.
+ */
+ topaque = BTPageGetOpaque(state->target);
+ child = palloc_btree_page(state, childblock);
+ copaque = BTPageGetOpaque(child);
+ maxoffset = PageGetMaxOffsetNumber(child);
+
+ /*
+ * Since we've already loaded the child block, combine this check with
+ * check for downlink connectivity.
+ */
+ bt_child_highkey_check(state, downlinkoffnum,
+ child, topaque->btpo_level);
+
+ /*
+ * Since there cannot be a concurrent VACUUM operation in readonly mode,
+ * and since a page has no links within other pages (siblings and parent)
+ * once it is marked fully deleted, it should be impossible to land on a
+ * fully deleted page.
+ *
+ * It does not quite make sense to enforce that the page cannot even be
+ * half-dead, despite the fact the downlink is modified at the same stage
+ * that the child leaf page is marked half-dead. That's incorrect because
+ * there may occasionally be multiple downlinks from a chain of pages
+ * undergoing deletion, where multiple successive calls are made to
+ * _bt_unlink_halfdead_page() by VACUUM before it can finally safely mark
+ * the leaf page as fully dead. While _bt_mark_page_halfdead() usually
+ * removes the downlink to the leaf page that is marked half-dead, that's
+ * not guaranteed, so it's possible we'll land on a half-dead page with a
+ * downlink due to an interrupted multi-level page deletion.
+ *
+ * We go ahead with our checks if the child page is half-dead. It's safe
+ * to do so because we do not test the child's high key, so it does not
+ * matter that the original high key will have been replaced by a dummy
+ * truncated high key within _bt_mark_page_halfdead(). All other page
+ * items are left intact on a half-dead page, so there is still something
+ * to test.
+ */
+ if (P_ISDELETED(copaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("downlink to deleted page found in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Parent block=%u child block=%u parent page lsn=%X/%X.",
+ state->targetblock, childblock,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+
+ for (offset = P_FIRSTDATAKEY(copaque);
+ offset <= maxoffset;
+ offset = OffsetNumberNext(offset))
+ {
+ /*
+ * Skip comparison of target page key against "negative infinity"
+ * item, if any. Checking it would indicate that it's not a strict
+ * lower bound, but that's only because of the hard-coding for
+ * negative infinity items within _bt_compare().
+ *
+ * If nbtree didn't truncate negative infinity tuples during internal
+ * page splits then we'd expect child's negative infinity key to be
+ * equal to the scankey/downlink from target/parent (it would be a
+ * "low key" in this hypothetical scenario, and so it would still need
+ * to be treated as a special case here).
+ *
+ * Negative infinity items can be thought of as a strict lower bound
+ * that works transitively, with the last non-negative-infinity pivot
+ * followed during a descent from the root as its "true" strict lower
+ * bound. Only a small number of negative infinity items are truly
+ * negative infinity; those that are the first items of leftmost
+ * internal pages. In more general terms, a negative infinity item is
+ * only negative infinity with respect to the subtree that the page is
+ * at the root of.
+ *
+ * See also: bt_rootdescend(), which can even detect transitive
+ * inconsistencies on cousin leaf pages.
+ */
+ if (offset_is_negative_infinity(copaque, offset))
+ continue;
+
+ if (!invariant_l_nontarget_offset(state, targetkey, childblock, child,
+ offset))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("down-link lower bound invariant violated for index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Parent block=%u child index tid=(%u,%u) parent page lsn=%X/%X.",
+ state->targetblock, childblock, offset,
+ LSN_FORMAT_ARGS(state->targetlsn))));
+ }
+
+ pfree(child);
+}
+
+/*
+ * Checks if page is missing a downlink that it should have.
+ *
+ * A page that lacks a downlink/parent may indicate corruption. However, we
+ * must account for the fact that a missing downlink can occasionally be
+ * encountered in a non-corrupt index. This can be due to an interrupted page
+ * split, or an interrupted multi-level page deletion (i.e. there was a hard
+ * crash or an error during a page split, or while VACUUM was deleting a
+ * multi-level chain of pages).
+ *
+ * Note that this can only be called in readonly mode, so there is no need to
+ * be concerned about concurrent page splits or page deletions.
+ */
+static void
+bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
+ BlockNumber blkno, Page page)
+{
+ BTPageOpaque opaque = BTPageGetOpaque(page);
+ ItemId itemid;
+ IndexTuple itup;
+ Page child;
+ BTPageOpaque copaque;
+ uint32 level;
+ BlockNumber childblk;
+ XLogRecPtr pagelsn;
+
+ Assert(state->readonly);
+ Assert(!P_IGNORE(opaque));
+
+ /* No next level up with downlinks to fingerprint from the true root */
+ if (P_ISROOT(opaque))
+ return;
+
+ pagelsn = PageGetLSN(page);
+
+ /*
+ * Incomplete (interrupted) page splits can account for the lack of a
+ * downlink. Some inserting transaction should eventually complete the
+ * page split in passing, when it notices that the left sibling page is
+ * P_INCOMPLETE_SPLIT().
+ *
+ * In general, VACUUM is not prepared for there to be no downlink to a
+ * page that it deletes. This is the main reason why the lack of a
+ * downlink can be reported as corruption here. It's not obvious that an
+ * invalid missing downlink can result in wrong answers to queries,
+ * though, since index scans that land on the child may end up
+ * consistently moving right. The handling of concurrent page splits (and
+ * page deletions) within _bt_moveright() cannot distinguish
+ * inconsistencies that last for a moment from inconsistencies that are
+ * permanent and irrecoverable.
+ *
+ * VACUUM isn't even prepared to delete pages that have no downlink due to
+ * an incomplete page split, but it can detect and reason about that case
+ * by design, so it shouldn't be taken to indicate corruption. See
+ * _bt_pagedel() for full details.
+ */
+ if (rightsplit)
+ {
+ ereport(DEBUG1,
+ (errcode(ERRCODE_NO_DATA),
+ errmsg_internal("harmless interrupted page split detected in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block=%u level=%u left sibling=%u page lsn=%X/%X.",
+ blkno, opaque->btpo_level,
+ opaque->btpo_prev,
+ LSN_FORMAT_ARGS(pagelsn))));
+ return;
+ }
+
+ /*
+ * Page under check is probably the "top parent" of a multi-level page
+ * deletion. We'll need to descend the subtree to make sure that
+ * descendant pages are consistent with that, though.
+ *
+ * If the page (which must be non-ignorable) is a leaf page, then clearly
+ * it can't be the top parent. The lack of a downlink is probably a
+ * symptom of a broad problem that could just as easily cause
+ * inconsistencies anywhere else.
+ */
+ if (P_ISLEAF(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("leaf index block lacks downlink in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block=%u page lsn=%X/%X.",
+ blkno,
+ LSN_FORMAT_ARGS(pagelsn))));
+
+ /* Descend from the given page, which is an internal page */
+ elog(DEBUG1, "checking for interrupted multi-level deletion due to missing downlink in index \"%s\"",
+ RelationGetRelationName(state->rel));
+
+ level = opaque->btpo_level;
+ itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+ itup = (IndexTuple) PageGetItem(page, itemid);
+ childblk = BTreeTupleGetDownLink(itup);
+ for (;;)
+ {
+ CHECK_FOR_INTERRUPTS();
+
+ child = palloc_btree_page(state, childblk);
+ copaque = BTPageGetOpaque(child);
+
+ if (P_ISLEAF(copaque))
+ break;
+
+ /* Do an extra sanity check in passing on internal pages */
+ if (copaque->btpo_level != level - 1)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("downlink points to block in index \"%s\" whose level is not one level down",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Top parent/under check block=%u block pointed to=%u expected level=%u level in pointed to block=%u.",
+ blkno, childblk,
+ level - 1, copaque->btpo_level)));
+
+ level = copaque->btpo_level;
+ itemid = PageGetItemIdCareful(state, childblk, child,
+ P_FIRSTDATAKEY(copaque));
+ itup = (IndexTuple) PageGetItem(child, itemid);
+ childblk = BTreeTupleGetDownLink(itup);
+ /* Be slightly more pro-active in freeing this memory, just in case */
+ pfree(child);
+ }
+
+ /*
+ * Since there cannot be a concurrent VACUUM operation in readonly mode,
+ * and since a page has no links within other pages (siblings and parent)
+ * once it is marked fully deleted, it should be impossible to land on a
+ * fully deleted page. See bt_child_check() for further details.
+ *
+ * The bt_child_check() P_ISDELETED() check is repeated here because
+ * bt_child_check() does not visit pages reachable through negative
+ * infinity items. Besides, bt_child_check() is unwilling to descend
+ * multiple levels. (The similar bt_child_check() P_ISDELETED() check
+ * within bt_check_level_from_leftmost() won't reach the page either,
+ * since the leaf's live siblings should have their sibling links updated
+ * to bypass the deletion target page when it is marked fully dead.)
+ *
+ * If this error is raised, it might be due to a previous multi-level page
+ * deletion that failed to realize that it wasn't yet safe to mark the
+ * leaf page as fully dead. A "dangling downlink" will still remain when
+ * this happens. The fact that the dangling downlink's page (the leaf's
+ * parent/ancestor page) lacked a downlink is incidental.
+ */
+ if (P_ISDELETED(copaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("downlink to deleted leaf page found in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Top parent/target block=%u leaf block=%u top parent/under check lsn=%X/%X.",
+ blkno, childblk,
+ LSN_FORMAT_ARGS(pagelsn))));
+
+ /*
+ * Iff leaf page is half-dead, its high key top parent link should point
+ * to what VACUUM considered to be the top parent page at the instant it
+ * was interrupted. Provided the high key link actually points to the
+ * page under check, the missing downlink we detected is consistent with
+ * there having been an interrupted multi-level page deletion. This means
+ * that the subtree with the page under check at its root (a page deletion
+ * chain) is in a consistent state, enabling VACUUM to resume deleting the
+ * entire chain the next time it encounters the half-dead leaf page.
+ */
+ if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
+ {
+ itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+ itup = (IndexTuple) PageGetItem(child, itemid);
+ if (BTreeTupleGetTopParent(itup) == blkno)
+ return;
+ }
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("internal index block lacks downlink in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Block=%u level=%u page lsn=%X/%X.",
+ blkno, opaque->btpo_level,
+ LSN_FORMAT_ARGS(pagelsn))));
+}
+
+/*
+ * Per-tuple callback from table_index_build_scan, used to determine if index has
+ * all the entries that definitely should have been observed in leaf pages of
+ * the target index (that is, all IndexTuples that were fingerprinted by our
+ * Bloom filter). All heapallindexed checks occur here.
+ *
+ * The redundancy between an index and the table it indexes provides a good
+ * opportunity to detect corruption, especially corruption within the table.
+ * The high level principle behind the verification performed here is that any
+ * IndexTuple that should be in an index following a fresh CREATE INDEX (based
+ * on the same index definition) should also have been in the original,
+ * existing index, which should have used exactly the same representation
+ *
+ * Since the overall structure of the index has already been verified, the most
+ * likely explanation for error here is a corrupt heap page (could be logical
+ * or physical corruption). Index corruption may still be detected here,
+ * though. Only readonly callers will have verified that left links and right
+ * links are in agreement, and so it's possible that a leaf page transposition
+ * within index is actually the source of corruption detected here (for
+ * !readonly callers). The checks performed only for readonly callers might
+ * more accurately frame the problem as a cross-page invariant issue (this
+ * could even be due to recovery not replaying all WAL records). The !readonly
+ * ERROR message raised here includes a HINT about retrying with readonly
+ * verification, just in case it's a cross-page invariant issue, though that
+ * isn't particularly likely.
+ *
+ * table_index_build_scan() expects to be able to find the root tuple when a
+ * heap-only tuple (the live tuple at the end of some HOT chain) needs to be
+ * indexed, in order to replace the actual tuple's TID with the root tuple's
+ * TID (which is what we're actually passed back here). The index build heap
+ * scan code will raise an error when a tuple that claims to be the root of the
+ * heap-only tuple's HOT chain cannot be located. This catches cases where the
+ * original root item offset/root tuple for a HOT chain indicates (for whatever
+ * reason) that the entire HOT chain is dead, despite the fact that the latest
+ * heap-only tuple should be indexed. When this happens, sequential scans may
+ * always give correct answers, and all indexes may be considered structurally
+ * consistent (i.e. the nbtree structural checks would not detect corruption).
+ * It may be the case that only index scans give wrong answers, and yet heap or
+ * SLRU corruption is the real culprit. (While it's true that LP_DEAD bit
+ * setting will probably also leave the index in a corrupt state before too
+ * long, the problem is nonetheless that there is heap corruption.)
+ *
+ * Heap-only tuple handling within table_index_build_scan() works in a way that
+ * helps us to detect index tuples that contain the wrong values (values that
+ * don't match the latest tuple in the HOT chain). This can happen when there
+ * is no superseding index tuple due to a faulty assessment of HOT safety,
+ * perhaps during the original CREATE INDEX. Because the latest tuple's
+ * contents are used with the root TID, an error will be raised when a tuple
+ * with the same TID but non-matching attribute values is passed back to us.
+ * Faulty assessment of HOT-safety was behind at least two distinct CREATE
+ * INDEX CONCURRENTLY bugs that made it into stable releases, one of which was
+ * undetected for many years. In short, the same principle that allows a
+ * REINDEX to repair corruption when there was an (undetected) broken HOT chain
+ * also allows us to detect the corruption in many cases.
+ */
+static void
+bt_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+ bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+ BtreeCheckState *state = (BtreeCheckState *) checkstate;
+ IndexTuple itup,
+ norm;
+
+ Assert(state->heapallindexed);
+
+ /* Generate a normalized index tuple for fingerprinting */
+ itup = index_form_tuple(RelationGetDescr(index), values, isnull);
+ itup->t_tid = *tid;
+ norm = bt_normalize_tuple(state, itup);
+
+ /* Probe Bloom filter -- tuple should be present */
+ if (bloom_lacks_element(state->filter, (unsigned char *) norm,
+ IndexTupleSize(norm)))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+ ItemPointerGetBlockNumber(&(itup->t_tid)),
+ ItemPointerGetOffsetNumber(&(itup->t_tid)),
+ RelationGetRelationName(state->heaprel),
+ RelationGetRelationName(state->rel)),
+ !state->readonly
+ ? errhint("Retrying verification using the function bt_index_parent_check() might provide a more specific error.")
+ : 0));
+
+ state->heaptuplespresent++;
+ pfree(itup);
+ /* Cannot leak memory here */
+ if (norm != itup)
+ pfree(norm);
+}
+
+/*
+ * Normalize an index tuple for fingerprinting.
+ *
+ * In general, index tuple formation is assumed to be deterministic by
+ * heapallindexed verification, and IndexTuples are assumed immutable. While
+ * the LP_DEAD bit is mutable in leaf pages, that's ItemId metadata, which is
+ * not fingerprinted. Normalization is required to compensate for corner
+ * cases where the determinism assumption doesn't quite work.
+ *
+ * There is currently one such case: index_form_tuple() does not try to hide
+ * the source TOAST state of input datums. The executor applies TOAST
+ * compression for heap tuples based on different criteria to the compression
+ * applied within btinsert()'s call to index_form_tuple(): it sometimes
+ * compresses more aggressively, resulting in compressed heap tuple datums but
+ * uncompressed corresponding index tuple datums. A subsequent heapallindexed
+ * verification will get a logically equivalent though bitwise unequal tuple
+ * from index_form_tuple(). False positive heapallindexed corruption reports
+ * could occur without normalizing away the inconsistency.
+ *
+ * Returned tuple is often caller's own original tuple. Otherwise, it is a
+ * new representation of caller's original index tuple, palloc()'d in caller's
+ * memory context.
+ *
+ * Note: This routine is not concerned with distinctions about the
+ * representation of tuples beyond those that might break heapallindexed
+ * verification. In particular, it won't try to normalize opclass-equal
+ * datums with potentially distinct representations (e.g., btree/numeric_ops
+ * index datums will not get their display scale normalized-away here).
+ * Caller does normalization for non-pivot tuples that have a posting list,
+ * since dummy CREATE INDEX callback code generates new tuples with the same
+ * normalized representation.
+ */
+static IndexTuple
+bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
+{
+ TupleDesc tupleDescriptor = RelationGetDescr(state->rel);
+ Datum normalized[INDEX_MAX_KEYS];
+ bool isnull[INDEX_MAX_KEYS];
+ bool toast_free[INDEX_MAX_KEYS];
+ bool formnewtup = false;
+ IndexTuple reformed;
+ int i;
+
+ /* Caller should only pass "logical" non-pivot tuples here */
+ Assert(!BTreeTupleIsPosting(itup) && !BTreeTupleIsPivot(itup));
+
+ /* Easy case: It's immediately clear that tuple has no varlena datums */
+ if (!IndexTupleHasVarwidths(itup))
+ return itup;
+
+ for (i = 0; i < tupleDescriptor->natts; i++)
+ {
+ Form_pg_attribute att;
+
+ att = TupleDescAttr(tupleDescriptor, i);
+
+ /* Assume untoasted/already normalized datum initially */
+ toast_free[i] = false;
+ normalized[i] = index_getattr(itup, att->attnum,
+ tupleDescriptor,
+ &isnull[i]);
+ if (att->attbyval || att->attlen != -1 || isnull[i])
+ continue;
+
+ /*
+ * Callers always pass a tuple that could safely be inserted into the
+ * index without further processing, so an external varlena header
+ * should never be encountered here
+ */
+ if (VARATT_IS_EXTERNAL(DatumGetPointer(normalized[i])))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+ ItemPointerGetBlockNumber(&(itup->t_tid)),
+ ItemPointerGetOffsetNumber(&(itup->t_tid)),
+ RelationGetRelationName(state->rel))));
+ else if (VARATT_IS_COMPRESSED(DatumGetPointer(normalized[i])))
+ {
+ formnewtup = true;
+ normalized[i] = PointerGetDatum(PG_DETOAST_DATUM(normalized[i]));
+ toast_free[i] = true;
+ }
+ }
+
+ /* Easier case: Tuple has varlena datums, none of which are compressed */
+ if (!formnewtup)
+ return itup;
+
+ /*
+ * Hard case: Tuple had compressed varlena datums that necessitate
+ * creating normalized version of the tuple from uncompressed input datums
+ * (normalized input datums). This is rather naive, but shouldn't be
+ * necessary too often.
+ *
+ * Note that we rely on deterministic index_form_tuple() TOAST compression
+ * of normalized input.
+ */
+ reformed = index_form_tuple(tupleDescriptor, normalized, isnull);
+ reformed->t_tid = itup->t_tid;
+
+ /* Cannot leak memory here */
+ for (i = 0; i < tupleDescriptor->natts; i++)
+ if (toast_free[i])
+ pfree(DatumGetPointer(normalized[i]));
+
+ return reformed;
+}
+
+/*
+ * Produce palloc()'d "plain" tuple for nth posting list entry/TID.
+ *
+ * In general, deduplication is not supposed to change the logical contents of
+ * an index. Multiple index tuples are merged together into one equivalent
+ * posting list index tuple when convenient.
+ *
+ * heapallindexed verification must normalize-away this variation in
+ * representation by converting posting list tuples into two or more "plain"
+ * tuples. Each tuple must be fingerprinted separately -- there must be one
+ * tuple for each corresponding Bloom filter probe during the heap scan.
+ *
+ * Note: Caller still needs to call bt_normalize_tuple() with returned tuple.
+ */
+static inline IndexTuple
+bt_posting_plain_tuple(IndexTuple itup, int n)
+{
+ Assert(BTreeTupleIsPosting(itup));
+
+ /* Returns non-posting-list tuple */
+ return _bt_form_posting(itup, BTreeTupleGetPostingN(itup, n), 1);
+}
+
+/*
+ * Search for itup in index, starting from fast root page. itup must be a
+ * non-pivot tuple. This is only supported with heapkeyspace indexes, since
+ * we rely on having fully unique keys to find a match with only a single
+ * visit to a leaf page, barring an interrupted page split, where we may have
+ * to move right. (A concurrent page split is impossible because caller must
+ * be readonly caller.)
+ *
+ * This routine can detect very subtle transitive consistency issues across
+ * more than one level of the tree. Leaf pages all have a high key (even the
+ * rightmost page has a conceptual positive infinity high key), but not a low
+ * key. Their downlink in parent is a lower bound, which along with the high
+ * key is almost enough to detect every possible inconsistency. A downlink
+ * separator key value won't always be available from parent, though, because
+ * the first items of internal pages are negative infinity items, truncated
+ * down to zero attributes during internal page splits. While it's true that
+ * bt_child_check() and the high key check can detect most imaginable key
+ * space problems, there are remaining problems it won't detect with non-pivot
+ * tuples in cousin leaf pages. Starting a search from the root for every
+ * existing leaf tuple detects small inconsistencies in upper levels of the
+ * tree that cannot be detected any other way. (Besides all this, this is
+ * probably also useful as a direct test of the code used by index scans
+ * themselves.)
+ */
+static bool
+bt_rootdescend(BtreeCheckState *state, IndexTuple itup)
+{
+ BTScanInsert key;
+ BTStack stack;
+ Buffer lbuf;
+ bool exists;
+
+ key = _bt_mkscankey(state->rel, itup);
+ Assert(key->heapkeyspace && key->scantid != NULL);
+
+ /*
+ * Search from root.
+ *
+ * Ideally, we would arrange to only move right within _bt_search() when
+ * an interrupted page split is detected (i.e. when the incomplete split
+ * bit is found to be set), but for now we accept the possibility that
+ * that could conceal an inconsistency.
+ */
+ Assert(state->readonly && state->rootdescend);
+ exists = false;
+ stack = _bt_search(state->rel, key, &lbuf, BT_READ, NULL);
+
+ if (BufferIsValid(lbuf))
+ {
+ BTInsertStateData insertstate;
+ OffsetNumber offnum;
+ Page page;
+
+ insertstate.itup = itup;
+ insertstate.itemsz = MAXALIGN(IndexTupleSize(itup));
+ insertstate.itup_key = key;
+ insertstate.postingoff = 0;
+ insertstate.bounds_valid = false;
+ insertstate.buf = lbuf;
+
+ /* Get matching tuple on leaf page */
+ offnum = _bt_binsrch_insert(state->rel, &insertstate);
+ /* Compare first >= matching item on leaf page, if any */
+ page = BufferGetPage(lbuf);
+ /* Should match on first heap TID when tuple has a posting list */
+ if (offnum <= PageGetMaxOffsetNumber(page) &&
+ insertstate.postingoff <= 0 &&
+ _bt_compare(state->rel, key, page, offnum) == 0)
+ exists = true;
+ _bt_relbuf(state->rel, lbuf);
+ }
+
+ _bt_freestack(stack);
+ pfree(key);
+
+ return exists;
+}
+
+/*
+ * Is particular offset within page (whose special state is passed by caller)
+ * the page negative-infinity item?
+ *
+ * As noted in comments above _bt_compare(), there is special handling of the
+ * first data item as a "negative infinity" item. The hard-coding within
+ * _bt_compare() makes comparing this item for the purposes of verification
+ * pointless at best, since the IndexTuple only contains a valid TID (a
+ * reference TID to child page).
+ */
+static inline bool
+offset_is_negative_infinity(BTPageOpaque opaque, OffsetNumber offset)
+{
+ /*
+ * For internal pages only, the first item after high key, if any, is
+ * negative infinity item. Internal pages always have a negative infinity
+ * item, whereas leaf pages never have one. This implies that negative
+ * infinity item is either first or second line item, or there is none
+ * within page.
+ *
+ * Negative infinity items are a special case among pivot tuples. They
+ * always have zero attributes, while all other pivot tuples always have
+ * nkeyatts attributes.
+ *
+ * Right-most pages don't have a high key, but could be said to
+ * conceptually have a "positive infinity" high key. Thus, there is a
+ * symmetry between down link items in parent pages, and high keys in
+ * children. Together, they represent the part of the key space that
+ * belongs to each page in the index. For example, all children of the
+ * root page will have negative infinity as a lower bound from root
+ * negative infinity downlink, and positive infinity as an upper bound
+ * (implicitly, from "imaginary" positive infinity high key in root).
+ */
+ return !P_ISLEAF(opaque) && offset == P_FIRSTDATAKEY(opaque);
+}
+
+/*
+ * Does the invariant hold that the key is strictly less than a given upper
+ * bound offset item?
+ *
+ * Verifies line pointer on behalf of caller.
+ *
+ * If this function returns false, convention is that caller throws error due
+ * to corruption.
+ */
+static inline bool
+invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
+ OffsetNumber upperbound)
+{
+ ItemId itemid;
+ int32 cmp;
+
+ Assert(key->pivotsearch);
+
+ /* Verify line pointer before checking tuple */
+ itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
+ upperbound);
+ /* pg_upgrade'd indexes may legally have equal sibling tuples */
+ if (!key->heapkeyspace)
+ return invariant_leq_offset(state, key, upperbound);
+
+ cmp = _bt_compare(state->rel, key, state->target, upperbound);
+
+ /*
+ * _bt_compare() is capable of determining that a scankey with a
+ * filled-out attribute is greater than pivot tuples where the comparison
+ * is resolved at a truncated attribute (value of attribute in pivot is
+ * minus infinity). However, it is not capable of determining that a
+ * scankey is _less than_ a tuple on the basis of a comparison resolved at
+ * _scankey_ minus infinity attribute. Complete an extra step to simulate
+ * having minus infinity values for omitted scankey attribute(s).
+ */
+ if (cmp == 0)
+ {
+ BTPageOpaque topaque;
+ IndexTuple ritup;
+ int uppnkeyatts;
+ ItemPointer rheaptid;
+ bool nonpivot;
+
+ ritup = (IndexTuple) PageGetItem(state->target, itemid);
+ topaque = BTPageGetOpaque(state->target);
+ nonpivot = P_ISLEAF(topaque) && upperbound >= P_FIRSTDATAKEY(topaque);
+
+ /* Get number of keys + heap TID for item to the right */
+ uppnkeyatts = BTreeTupleGetNKeyAtts(ritup, state->rel);
+ rheaptid = BTreeTupleGetHeapTIDCareful(state, ritup, nonpivot);
+
+ /* Heap TID is tiebreaker key attribute */
+ if (key->keysz == uppnkeyatts)
+ return key->scantid == NULL && rheaptid != NULL;
+
+ return key->keysz < uppnkeyatts;
+ }
+
+ return cmp < 0;
+}
+
+/*
+ * Does the invariant hold that the key is less than or equal to a given upper
+ * bound offset item?
+ *
+ * Caller should have verified that upperbound's line pointer is consistent
+ * using PageGetItemIdCareful() call.
+ *
+ * If this function returns false, convention is that caller throws error due
+ * to corruption.
+ */
+static inline bool
+invariant_leq_offset(BtreeCheckState *state, BTScanInsert key,
+ OffsetNumber upperbound)
+{
+ int32 cmp;
+
+ Assert(key->pivotsearch);
+
+ cmp = _bt_compare(state->rel, key, state->target, upperbound);
+
+ return cmp <= 0;
+}
+
+/*
+ * Does the invariant hold that the key is strictly greater than a given lower
+ * bound offset item?
+ *
+ * Caller should have verified that lowerbound's line pointer is consistent
+ * using PageGetItemIdCareful() call.
+ *
+ * If this function returns false, convention is that caller throws error due
+ * to corruption.
+ */
+static inline bool
+invariant_g_offset(BtreeCheckState *state, BTScanInsert key,
+ OffsetNumber lowerbound)
+{
+ int32 cmp;
+
+ Assert(key->pivotsearch);
+
+ cmp = _bt_compare(state->rel, key, state->target, lowerbound);
+
+ /* pg_upgrade'd indexes may legally have equal sibling tuples */
+ if (!key->heapkeyspace)
+ return cmp >= 0;
+
+ /*
+ * No need to consider the possibility that scankey has attributes that we
+ * need to force to be interpreted as negative infinity. _bt_compare() is
+ * able to determine that scankey is greater than negative infinity. The
+ * distinction between "==" and "<" isn't interesting here, since
+ * corruption is indicated either way.
+ */
+ return cmp > 0;
+}
+
+/*
+ * Does the invariant hold that the key is strictly less than a given upper
+ * bound offset item, with the offset relating to a caller-supplied page that
+ * is not the current target page?
+ *
+ * Caller's non-target page is a child page of the target, checked as part of
+ * checking a property of the target page (i.e. the key comes from the
+ * target). Verifies line pointer on behalf of caller.
+ *
+ * If this function returns false, convention is that caller throws error due
+ * to corruption.
+ */
+static inline bool
+invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
+ BlockNumber nontargetblock, Page nontarget,
+ OffsetNumber upperbound)
+{
+ ItemId itemid;
+ int32 cmp;
+
+ Assert(key->pivotsearch);
+
+ /* Verify line pointer before checking tuple */
+ itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
+ upperbound);
+ cmp = _bt_compare(state->rel, key, nontarget, upperbound);
+
+ /* pg_upgrade'd indexes may legally have equal sibling tuples */
+ if (!key->heapkeyspace)
+ return cmp <= 0;
+
+ /* See invariant_l_offset() for an explanation of this extra step */
+ if (cmp == 0)
+ {
+ IndexTuple child;
+ int uppnkeyatts;
+ ItemPointer childheaptid;
+ BTPageOpaque copaque;
+ bool nonpivot;
+
+ child = (IndexTuple) PageGetItem(nontarget, itemid);
+ copaque = BTPageGetOpaque(nontarget);
+ nonpivot = P_ISLEAF(copaque) && upperbound >= P_FIRSTDATAKEY(copaque);
+
+ /* Get number of keys + heap TID for child/non-target item */
+ uppnkeyatts = BTreeTupleGetNKeyAtts(child, state->rel);
+ childheaptid = BTreeTupleGetHeapTIDCareful(state, child, nonpivot);
+
+ /* Heap TID is tiebreaker key attribute */
+ if (key->keysz == uppnkeyatts)
+ return key->scantid == NULL && childheaptid != NULL;
+
+ return key->keysz < uppnkeyatts;
+ }
+
+ return cmp < 0;
+}
+
+/*
+ * Given a block number of a B-Tree page, return page in palloc()'d memory.
+ * While at it, perform some basic checks of the page.
+ *
+ * There is never an attempt to get a consistent view of multiple pages using
+ * multiple concurrent buffer locks; in general, we only acquire a single pin
+ * and buffer lock at a time, which is often all that the nbtree code requires.
+ * (Actually, bt_recheck_sibling_links couples buffer locks, which is the only
+ * exception to this general rule.)
+ *
+ * Operating on a copy of the page is useful because it prevents control
+ * getting stuck in an uninterruptible state when an underlying operator class
+ * misbehaves.
+ */
+static Page
+palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum)
+{
+ Buffer buffer;
+ Page page;
+ BTPageOpaque opaque;
+ OffsetNumber maxoffset;
+
+ page = palloc(BLCKSZ);
+
+ /*
+ * We copy the page into local storage to avoid holding pin on the buffer
+ * longer than we must.
+ */
+ buffer = ReadBufferExtended(state->rel, MAIN_FORKNUM, blocknum, RBM_NORMAL,
+ state->checkstrategy);
+ LockBuffer(buffer, BT_READ);
+
+ /*
+ * Perform the same basic sanity checking that nbtree itself performs for
+ * every page:
+ */
+ _bt_checkpage(state->rel, buffer);
+
+ /* Only use copy of page in palloc()'d memory */
+ memcpy(page, BufferGetPage(buffer), BLCKSZ);
+ UnlockReleaseBuffer(buffer);
+
+ opaque = BTPageGetOpaque(page);
+
+ if (P_ISMETA(opaque) && blocknum != BTREE_METAPAGE)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("invalid meta page found at block %u in index \"%s\"",
+ blocknum, RelationGetRelationName(state->rel))));
+
+ /* Check page from block that ought to be meta page */
+ if (blocknum == BTREE_METAPAGE)
+ {
+ BTMetaPageData *metad = BTPageGetMeta(page);
+
+ if (!P_ISMETA(opaque) ||
+ metad->btm_magic != BTREE_MAGIC)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index \"%s\" meta page is corrupt",
+ RelationGetRelationName(state->rel))));
+
+ if (metad->btm_version < BTREE_MIN_VERSION ||
+ metad->btm_version > BTREE_VERSION)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("version mismatch in index \"%s\": file version %d, "
+ "current version %d, minimum supported version %d",
+ RelationGetRelationName(state->rel),
+ metad->btm_version, BTREE_VERSION,
+ BTREE_MIN_VERSION)));
+
+ /* Finished with metapage checks */
+ return page;
+ }
+
+ /*
+ * Deleted pages that still use the old 32-bit XID representation have no
+ * sane "level" field because they type pun the field, but all other pages
+ * (including pages deleted on Postgres 14+) have a valid value.
+ */
+ if (!P_ISDELETED(opaque) || P_HAS_FULLXID(opaque))
+ {
+ /* Okay, no reason not to trust btpo_level field from page */
+
+ if (P_ISLEAF(opaque) && opaque->btpo_level != 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("invalid leaf page level %u for block %u in index \"%s\"",
+ opaque->btpo_level, blocknum,
+ RelationGetRelationName(state->rel))));
+
+ if (!P_ISLEAF(opaque) && opaque->btpo_level == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("invalid internal page level 0 for block %u in index \"%s\"",
+ blocknum,
+ RelationGetRelationName(state->rel))));
+ }
+
+ /*
+ * Sanity checks for number of items on page.
+ *
+ * As noted at the beginning of _bt_binsrch(), an internal page must have
+ * children, since there must always be a negative infinity downlink
+ * (there may also be a highkey). In the case of non-rightmost leaf
+ * pages, there must be at least a highkey. The exceptions are deleted
+ * pages, which contain no items.
+ *
+ * This is correct when pages are half-dead, since internal pages are
+ * never half-dead, and leaf pages must have a high key when half-dead
+ * (the rightmost page can never be deleted). It's also correct with
+ * fully deleted pages: _bt_unlink_halfdead_page() doesn't change anything
+ * about the target page other than setting the page as fully dead, and
+ * setting its xact field. In particular, it doesn't change the sibling
+ * links in the deletion target itself, since they're required when index
+ * scans land on the deletion target, and then need to move right (or need
+ * to move left, in the case of backward index scans).
+ */
+ maxoffset = PageGetMaxOffsetNumber(page);
+ if (maxoffset > MaxIndexTuplesPerPage)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("Number of items on block %u of index \"%s\" exceeds MaxIndexTuplesPerPage (%u)",
+ blocknum, RelationGetRelationName(state->rel),
+ MaxIndexTuplesPerPage)));
+
+ if (!P_ISLEAF(opaque) && !P_ISDELETED(opaque) && maxoffset < P_FIRSTDATAKEY(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("internal block %u in index \"%s\" lacks high key and/or at least one downlink",
+ blocknum, RelationGetRelationName(state->rel))));
+
+ if (P_ISLEAF(opaque) && !P_ISDELETED(opaque) && !P_RIGHTMOST(opaque) && maxoffset < P_HIKEY)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("non-rightmost leaf block %u in index \"%s\" lacks high key item",
+ blocknum, RelationGetRelationName(state->rel))));
+
+ /*
+ * In general, internal pages are never marked half-dead, except on
+ * versions of Postgres prior to 9.4, where it can be valid transient
+ * state. This state is nonetheless treated as corruption by VACUUM on
+ * from version 9.4 on, so do the same here. See _bt_pagedel() for full
+ * details.
+ */
+ if (!P_ISLEAF(opaque) && P_ISHALFDEAD(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("internal page block %u in index \"%s\" is half-dead",
+ blocknum, RelationGetRelationName(state->rel)),
+ errhint("This can be caused by an interrupted VACUUM in version 9.3 or older, before upgrade. Please REINDEX it.")));
+
+ /*
+ * Check that internal pages have no garbage items, and that no page has
+ * an invalid combination of deletion-related page level flags
+ */
+ if (!P_ISLEAF(opaque) && P_HAS_GARBAGE(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("internal page block %u in index \"%s\" has garbage items",
+ blocknum, RelationGetRelationName(state->rel))));
+
+ if (P_HAS_FULLXID(opaque) && !P_ISDELETED(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("full transaction id page flag appears in non-deleted block %u in index \"%s\"",
+ blocknum, RelationGetRelationName(state->rel))));
+
+ if (P_ISDELETED(opaque) && P_ISHALFDEAD(opaque))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("deleted page block %u in index \"%s\" is half-dead",
+ blocknum, RelationGetRelationName(state->rel))));
+
+ return page;
+}
+
+/*
+ * _bt_mkscankey() wrapper that automatically prevents insertion scankey from
+ * being considered greater than the pivot tuple that its values originated
+ * from (or some other identical pivot tuple) in the common case where there
+ * are truncated/minus infinity attributes. Without this extra step, there
+ * are forms of corruption that amcheck could theoretically fail to report.
+ *
+ * For example, invariant_g_offset() might miss a cross-page invariant failure
+ * on an internal level if the scankey built from the first item on the
+ * target's right sibling page happened to be equal to (not greater than) the
+ * last item on target page. The !pivotsearch tiebreaker in _bt_compare()
+ * might otherwise cause amcheck to assume (rather than actually verify) that
+ * the scankey is greater.
+ */
+static inline BTScanInsert
+bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
+{
+ BTScanInsert skey;
+
+ skey = _bt_mkscankey(rel, itup);
+ skey->pivotsearch = true;
+
+ return skey;
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself. For
+ * example, there is no bounds checking in PageGetItem(). Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+static ItemId
+PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
+ OffsetNumber offset)
+{
+ ItemId itemid = PageGetItemId(page, offset);
+
+ if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+ BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("line pointer points past end of tuple space in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+ block, offset, ItemIdGetOffset(itemid),
+ ItemIdGetLength(itemid),
+ ItemIdGetFlags(itemid))));
+
+ /*
+ * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+ * never uses either. Verify that line pointer has storage, too, since
+ * even LP_DEAD items should within nbtree.
+ */
+ if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+ ItemIdGetLength(itemid) == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("invalid line pointer storage in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+ block, offset, ItemIdGetOffset(itemid),
+ ItemIdGetLength(itemid),
+ ItemIdGetFlags(itemid))));
+
+ return itemid;
+}
+
+/*
+ * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
+ * cases where that is mandatory (i.e. for non-pivot tuples)
+ */
+static inline ItemPointer
+BTreeTupleGetHeapTIDCareful(BtreeCheckState *state, IndexTuple itup,
+ bool nonpivot)
+{
+ ItemPointer htid;
+
+ /*
+ * Caller determines whether this is supposed to be a pivot or non-pivot
+ * tuple using page type and item offset number. Verify that tuple
+ * metadata agrees with this.
+ */
+ Assert(state->heapkeyspace);
+ if (BTreeTupleIsPivot(itup) && nonpivot)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("block %u or its right sibling block or child block in index \"%s\" has unexpected pivot tuple",
+ state->targetblock,
+ RelationGetRelationName(state->rel))));
+
+ if (!BTreeTupleIsPivot(itup) && !nonpivot)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg_internal("block %u or its right sibling block or child block in index \"%s\" has unexpected non-pivot tuple",
+ state->targetblock,
+ RelationGetRelationName(state->rel))));
+
+ htid = BTreeTupleGetHeapTID(itup);
+ if (!ItemPointerIsValid(htid) && nonpivot)
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("block %u or its right sibling block or child block in index \"%s\" contains non-pivot tuple that lacks a heap TID",
+ state->targetblock,
+ RelationGetRelationName(state->rel))));
+
+ return htid;
+}
+
+/*
+ * Return the "pointed to" TID for itup, which is used to generate a
+ * descriptive error message. itup must be a "data item" tuple (it wouldn't
+ * make much sense to call here with a high key tuple, since there won't be a
+ * valid downlink/block number to display).
+ *
+ * Returns either a heap TID (which will be the first heap TID in posting list
+ * if itup is posting list tuple), or a TID that contains downlink block
+ * number, plus some encoded metadata (e.g., the number of attributes present
+ * in itup).
+ */
+static inline ItemPointer
+BTreeTupleGetPointsToTID(IndexTuple itup)
+{
+ /*
+ * Rely on the assumption that !heapkeyspace internal page data items will
+ * correctly return TID with downlink here -- BTreeTupleGetHeapTID() won't
+ * recognize it as a pivot tuple, but everything still works out because
+ * the t_tid field is still returned
+ */
+ if (!BTreeTupleIsPivot(itup))
+ return BTreeTupleGetHeapTID(itup);
+
+ /* Pivot tuple returns TID with downlink block (heapkeyspace variant) */
+ return &itup->t_tid;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 18:10:36 +0000