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CREATE EXTENSION pg_freespacemap;
CREATE TABLE freespace_tab (c1 int) WITH (autovacuum_enabled = off);
CREATE INDEX freespace_brin ON freespace_tab USING brin (c1);
CREATE INDEX freespace_btree ON freespace_tab USING btree (c1);
CREATE INDEX freespace_hash ON freespace_tab USING hash (c1);
-- report all the sizes of the FSMs for all the relation blocks.
WITH rel AS (SELECT oid::regclass AS id FROM pg_class WHERE relname ~ 'freespace')
SELECT rel.id, fsm.blkno, (fsm.avail > 0) AS is_avail
FROM rel, LATERAL pg_freespace(rel.id) AS fsm
ORDER BY 1, 2;
id | blkno | is_avail
-----------------+-------+----------
freespace_brin | 0 | f
freespace_brin | 1 | f
freespace_brin | 2 | t
freespace_btree | 0 | f
freespace_hash | 0 | f
freespace_hash | 1 | f
freespace_hash | 2 | f
freespace_hash | 3 | f
freespace_hash | 4 | f
freespace_hash | 5 | f
freespace_hash | 6 | f
freespace_hash | 7 | f
freespace_hash | 8 | f
freespace_hash | 9 | f
(14 rows)
INSERT INTO freespace_tab VALUES (1);
VACUUM freespace_tab;
WITH rel AS (SELECT oid::regclass AS id FROM pg_class WHERE relname ~ 'freespace')
SELECT rel.id, fsm.blkno, (fsm.avail > 0) AS is_avail
FROM rel, LATERAL pg_freespace(rel.id) AS fsm
ORDER BY 1, 2;
id | blkno | is_avail
-----------------+-------+----------
freespace_tab | 0 | t
freespace_brin | 0 | f
freespace_brin | 1 | f
freespace_brin | 2 | t
freespace_btree | 0 | f
freespace_btree | 1 | f
freespace_hash | 0 | f
freespace_hash | 1 | f
freespace_hash | 2 | f
freespace_hash | 3 | f
freespace_hash | 4 | f
freespace_hash | 5 | f
freespace_hash | 6 | f
freespace_hash | 7 | f
freespace_hash | 8 | f
freespace_hash | 9 | f
(16 rows)
DELETE FROM freespace_tab;
VACUUM freespace_tab;
WITH rel AS (SELECT oid::regclass AS id FROM pg_class WHERE relname ~ 'freespace')
SELECT rel.id, fsm.blkno, (fsm.avail > 0) AS is_avail
FROM rel, LATERAL pg_freespace(rel.id) AS fsm
ORDER BY 1, 2;
id | blkno | is_avail
-----------------+-------+----------
freespace_brin | 0 | f
freespace_brin | 1 | f
freespace_brin | 2 | t
freespace_btree | 0 | f
freespace_btree | 1 | f
freespace_hash | 0 | f
freespace_hash | 1 | f
freespace_hash | 2 | f
freespace_hash | 3 | f
freespace_hash | 4 | f
freespace_hash | 5 | f
freespace_hash | 6 | f
freespace_hash | 7 | f
freespace_hash | 8 | f
freespace_hash | 9 | f
(15 rows)
-- failures with incorrect block number
SELECT * FROM pg_freespace('freespace_tab', -1);
ERROR: invalid block number
SELECT * FROM pg_freespace('freespace_tab', 4294967295);
ERROR: invalid block number
DROP TABLE freespace_tab;
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