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--
-- Test Statistics Collector
--
-- Must be run after tenk2 has been created (by create_table),
-- populated (by create_misc) and indexed (by create_index).
--
-- conditio sine qua non
SHOW track_counts; -- must be on
-- ensure that both seqscan and indexscan plans are allowed
SET enable_seqscan TO on;
SET enable_indexscan TO on;
-- for the moment, we don't want index-only scans here
SET enable_indexonlyscan TO off;
-- save counters
CREATE TABLE prevstats AS
SELECT t.seq_scan, t.seq_tup_read, t.idx_scan, t.idx_tup_fetch,
(b.heap_blks_read + b.heap_blks_hit) AS heap_blks,
(b.idx_blks_read + b.idx_blks_hit) AS idx_blks,
pg_stat_get_snapshot_timestamp() as snap_ts
FROM pg_catalog.pg_stat_user_tables AS t,
pg_catalog.pg_statio_user_tables AS b
WHERE t.relname='tenk2' AND b.relname='tenk2';
-- function to wait for counters to advance
create function wait_for_stats() returns void as $$
declare
start_time timestamptz := clock_timestamp();
updated1 bool;
updated2 bool;
updated3 bool;
updated4 bool;
begin
-- we don't want to wait forever; loop will exit after 30 seconds
for i in 1 .. 300 loop
-- With parallel query, the seqscan and indexscan on tenk2 might be done
-- in parallel worker processes, which will send their stats counters
-- asynchronously to what our own session does. So we must check for
-- those counts to be registered separately from the update counts.
-- check to see if seqscan has been sensed
SELECT (st.seq_scan >= pr.seq_scan + 1) INTO updated1
FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr
WHERE st.relname='tenk2' AND cl.relname='tenk2';
-- check to see if indexscan has been sensed
SELECT (st.idx_scan >= pr.idx_scan + 1) INTO updated2
FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr
WHERE st.relname='tenk2' AND cl.relname='tenk2';
-- check to see if all updates have been sensed
SELECT (n_tup_ins > 0) INTO updated3
FROM pg_stat_user_tables WHERE relname='trunc_stats_test4';
-- We must also check explicitly that pg_stat_get_snapshot_timestamp has
-- advanced, because that comes from the global stats file which might
-- be older than the per-DB stats file we got the other values from.
SELECT (pr.snap_ts < pg_stat_get_snapshot_timestamp()) INTO updated4
FROM prevstats AS pr;
exit when updated1 and updated2 and updated3 and updated4;
-- wait a little
perform pg_sleep_for('100 milliseconds');
-- reset stats snapshot so we can test again
perform pg_stat_clear_snapshot();
end loop;
-- report time waited in postmaster log (where it won't change test output)
raise log 'wait_for_stats delayed % seconds',
extract(epoch from clock_timestamp() - start_time);
end
$$ language plpgsql;
-- test effects of TRUNCATE on n_live_tup/n_dead_tup counters
CREATE TABLE trunc_stats_test(id serial);
CREATE TABLE trunc_stats_test1(id serial, stuff text);
CREATE TABLE trunc_stats_test2(id serial);
CREATE TABLE trunc_stats_test3(id serial, stuff text);
CREATE TABLE trunc_stats_test4(id serial);
-- check that n_live_tup is reset to 0 after truncate
INSERT INTO trunc_stats_test DEFAULT VALUES;
INSERT INTO trunc_stats_test DEFAULT VALUES;
INSERT INTO trunc_stats_test DEFAULT VALUES;
TRUNCATE trunc_stats_test;
-- test involving a truncate in a transaction; 4 ins but only 1 live
INSERT INTO trunc_stats_test1 DEFAULT VALUES;
INSERT INTO trunc_stats_test1 DEFAULT VALUES;
INSERT INTO trunc_stats_test1 DEFAULT VALUES;
UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
DELETE FROM trunc_stats_test1 WHERE id = 3;
BEGIN;
UPDATE trunc_stats_test1 SET id = id + 100;
TRUNCATE trunc_stats_test1;
INSERT INTO trunc_stats_test1 DEFAULT VALUES;
COMMIT;
-- use a savepoint: 1 insert, 1 live
BEGIN;
INSERT INTO trunc_stats_test2 DEFAULT VALUES;
INSERT INTO trunc_stats_test2 DEFAULT VALUES;
SAVEPOINT p1;
INSERT INTO trunc_stats_test2 DEFAULT VALUES;
TRUNCATE trunc_stats_test2;
INSERT INTO trunc_stats_test2 DEFAULT VALUES;
RELEASE SAVEPOINT p1;
COMMIT;
-- rollback a savepoint: this should count 4 inserts and have 2
-- live tuples after commit (and 2 dead ones due to aborted subxact)
BEGIN;
INSERT INTO trunc_stats_test3 DEFAULT VALUES;
INSERT INTO trunc_stats_test3 DEFAULT VALUES;
SAVEPOINT p1;
INSERT INTO trunc_stats_test3 DEFAULT VALUES;
INSERT INTO trunc_stats_test3 DEFAULT VALUES;
TRUNCATE trunc_stats_test3;
INSERT INTO trunc_stats_test3 DEFAULT VALUES;
ROLLBACK TO SAVEPOINT p1;
COMMIT;
-- rollback a truncate: this should count 2 inserts and produce 2 dead tuples
BEGIN;
INSERT INTO trunc_stats_test4 DEFAULT VALUES;
INSERT INTO trunc_stats_test4 DEFAULT VALUES;
TRUNCATE trunc_stats_test4;
INSERT INTO trunc_stats_test4 DEFAULT VALUES;
ROLLBACK;
-- do a seqscan
SELECT count(*) FROM tenk2;
-- do an indexscan
-- make sure it is not a bitmap scan, which might skip fetching heap tuples
SET enable_bitmapscan TO off;
SELECT count(*) FROM tenk2 WHERE unique1 = 1;
RESET enable_bitmapscan;
-- We can't just call wait_for_stats() at this point, because we only
-- transmit stats when the session goes idle, and we probably didn't
-- transmit the last couple of counts yet thanks to the rate-limiting logic
-- in pgstat_report_stat(). But instead of waiting for the rate limiter's
-- timeout to elapse, let's just start a new session. The old one will
-- then send its stats before dying.
\c -
-- wait for stats collector to update
SELECT wait_for_stats();
-- check effects
SELECT relname, n_tup_ins, n_tup_upd, n_tup_del, n_live_tup, n_dead_tup
FROM pg_stat_user_tables
WHERE relname like 'trunc_stats_test%' order by relname;
SELECT st.seq_scan >= pr.seq_scan + 1,
st.seq_tup_read >= pr.seq_tup_read + cl.reltuples,
st.idx_scan >= pr.idx_scan + 1,
st.idx_tup_fetch >= pr.idx_tup_fetch + 1
FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr
WHERE st.relname='tenk2' AND cl.relname='tenk2';
SELECT st.heap_blks_read + st.heap_blks_hit >= pr.heap_blks + cl.relpages,
st.idx_blks_read + st.idx_blks_hit >= pr.idx_blks + 1
FROM pg_statio_user_tables AS st, pg_class AS cl, prevstats AS pr
WHERE st.relname='tenk2' AND cl.relname='tenk2';
SELECT pr.snap_ts < pg_stat_get_snapshot_timestamp() as snapshot_newer
FROM prevstats AS pr;
DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_test3, trunc_stats_test4;
DROP TABLE prevstats;
-- End of Stats Test
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