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tests: Expand temp table tests to some pin related matters

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Added tests:
- recovery from running out of unpinned local buffers
- that we don't run out of unpinned buffers due to read stream (only recently
  fixed, in 92fc6856cb4)
- temp tables can't be dropped while in use by cursors

Discussion: weskknhckugbdm2yt7sa2uq53xlsax67gcdkac34sanb7qpd3p@hcc2wadao5wy
Discussion: https://postgr.es/m/ge6nsuddurhpmll3xj22vucvqwp4agqz6ndtcf2mhyeydzarst@l75dman5x53p
This commit is contained in:
Andres Freund 2025-03-17 14:12:44 -04:00
parent 99aeb84703
commit 1a22a8a0f1
3 changed files with 264 additions and 1 deletions
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156
src/test/regress/expected/temp.out
View File

@ -410,3 +410,159 @@ SELECT current_schema() ~ 'pg_temp' AS is_temp_schema;
PREPARE TRANSACTION 'twophase_search'; PREPARE TRANSACTION 'twophase_search';
ERROR: cannot PREPARE a transaction that has operated on temporary objects ERROR: cannot PREPARE a transaction that has operated on temporary objects
-- Tests to verify we recover correctly from exhausting buffer pins and
-- related matters.
-- use lower possible buffer limit to make the test cheaper
\c
SET temp_buffers = 100;
CREATE TEMPORARY TABLE test_temp(a int not null unique, b TEXT not null, cnt int not null);
INSERT INTO test_temp SELECT generate_series(1, 10000) as id, repeat('a', 200), 0;
-- should be at least 2x as large than temp_buffers
SELECT pg_relation_size('test_temp') / current_setting('block_size')::int8 > 200;
?column?
----------
t
(1 row)
-- Don't want cursor names and plpgsql function lines in the error messages
\set VERBOSITY terse
/* helper function to create cursors for each page in [p_start, p_end] */
CREATE FUNCTION test_temp_pin(p_start int, p_end int)
RETURNS void
LANGUAGE plpgsql
AS $f$
DECLARE
cursorname text;
query text;
BEGIN
FOR i IN p_start..p_end LOOP
cursorname = 'c_'||i;
query = format($q$DECLARE %I CURSOR FOR SELECT ctid FROM test_temp WHERE ctid >= '( %s, 1)'::tid $q$, cursorname, i);
EXECUTE query;
EXECUTE 'FETCH NEXT FROM '||cursorname;
-- for test development
-- RAISE NOTICE '%: %', cursorname, query;
END LOOP;
END;
$f$;
-- Test overflow of temp table buffers is handled correctly
BEGIN;
-- should work, below max
SELECT test_temp_pin(0, 9);
test_temp_pin
---------------
(1 row)
-- should fail, too many buffers pinned
SELECT test_temp_pin(10, 105);
ERROR: no empty local buffer available
ROLLBACK;
BEGIN;
-- have some working cursors to test after errors
SELECT test_temp_pin(0, 9);
test_temp_pin
---------------
(1 row)
FETCH NEXT FROM c_3;
ctid
-------
(3,2)
(1 row)
-- exhaust buffer pins in subtrans, check things work after
SAVEPOINT rescue_me;
SELECT test_temp_pin(10, 105);
ERROR: no empty local buffer available
ROLLBACK TO SAVEPOINT rescue_me;
-- pre-subtrans cursors continue to work
FETCH NEXT FROM c_3;
ctid
-------
(3,3)
(1 row)
-- new cursors with pins can be created after subtrans rollback
SELECT test_temp_pin(10, 94);
test_temp_pin
---------------
(1 row)
-- Check that read streams deal with lower number of pins available
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
count | max_a | min_a | max_cnt
-------+-------+-------+---------
10000 | 10000 | 1 | 0
(1 row)
ROLLBACK;
-- Check that temp tables with existing cursors can't be dropped.
BEGIN;
SELECT test_temp_pin(0, 1);
test_temp_pin
---------------
(1 row)
DROP TABLE test_temp;
ERROR: cannot DROP TABLE "test_temp" because it is being used by active queries in this session
COMMIT;
-- Check that temp tables with existing cursors can't be dropped.
BEGIN;
SELECT test_temp_pin(0, 1);
test_temp_pin
---------------
(1 row)
TRUNCATE test_temp;
ERROR: cannot TRUNCATE "test_temp" because it is being used by active queries in this session
COMMIT;
-- Check that temp tables that are dropped in transaction that's rolled back
-- preserve buffer contents
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
count | max_a | min_a | max_cnt
-------+-------+-------+---------
10000 | 10000 | 1 | 0
(1 row)
INSERT INTO test_temp(a, b, cnt) VALUES (-1, '', 0);
BEGIN;
INSERT INTO test_temp(a, b, cnt) VALUES (-2, '', 0);
DROP TABLE test_temp;
ROLLBACK;
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
count | max_a | min_a | max_cnt
-------+-------+-------+---------
10001 | 10000 | -1 | 0
(1 row)
-- Check that temp table drop is transactional and preserves dirty
-- buffer contents
UPDATE test_temp SET cnt = cnt + 1 WHERE a = -1;
BEGIN;
DROP TABLE test_temp;
ROLLBACK;
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
count | max_a | min_a | max_cnt
-------+-------+-------+---------
10001 | 10000 | -1 | 1
(1 row)
-- Check that temp table truncation is transactional and preserves dirty
-- buffer contents
UPDATE test_temp SET cnt = cnt + 1 WHERE a = -1;
BEGIN;
TRUNCATE test_temp;
ROLLBACK;
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
count | max_a | min_a | max_cnt
-------+-------+-------+---------
10001 | 10000 | -1 | 2
(1 row)
-- cleanup
DROP FUNCTION test_temp_pin(int, int);

2
src/test/regress/parallel_schedule
View File

@ -108,7 +108,7 @@ test: json jsonb json_encoding jsonpath jsonpath_encoding jsonb_jsonpath sqljson
# ---------- # ----------
# Another group of parallel tests # Another group of parallel tests
# with depends on create_misc # with depends on create_misc
# NB: temp.sql does a reconnect which transiently uses 2 connections, # NB: temp.sql does reconnects which transiently use 2 connections,
# so keep this parallel group to at most 19 tests # so keep this parallel group to at most 19 tests
# ---------- # ----------
test: plancache limit plpgsql copy2 temp domain rangefuncs prepare conversion truncate alter_table sequence polymorphism rowtypes returning largeobject with xml test: plancache limit plpgsql copy2 temp domain rangefuncs prepare conversion truncate alter_table sequence polymorphism rowtypes returning largeobject with xml

107
src/test/regress/sql/temp.sql
View File

@ -311,3 +311,110 @@ SET search_path TO 'pg_temp';
BEGIN; BEGIN;
SELECT current_schema() ~ 'pg_temp' AS is_temp_schema; SELECT current_schema() ~ 'pg_temp' AS is_temp_schema;
PREPARE TRANSACTION 'twophase_search'; PREPARE TRANSACTION 'twophase_search';
-- Tests to verify we recover correctly from exhausting buffer pins and
-- related matters.
-- use lower possible buffer limit to make the test cheaper
\c
SET temp_buffers = 100;
CREATE TEMPORARY TABLE test_temp(a int not null unique, b TEXT not null, cnt int not null);
INSERT INTO test_temp SELECT generate_series(1, 10000) as id, repeat('a', 200), 0;
-- should be at least 2x as large than temp_buffers
SELECT pg_relation_size('test_temp') / current_setting('block_size')::int8 > 200;
-- Don't want cursor names and plpgsql function lines in the error messages
\set VERBOSITY terse
/* helper function to create cursors for each page in [p_start, p_end] */
CREATE FUNCTION test_temp_pin(p_start int, p_end int)
RETURNS void
LANGUAGE plpgsql
AS $f$
DECLARE
cursorname text;
query text;
BEGIN
FOR i IN p_start..p_end LOOP
cursorname = 'c_'||i;
query = format($q$DECLARE %I CURSOR FOR SELECT ctid FROM test_temp WHERE ctid >= '( %s, 1)'::tid $q$, cursorname, i);
EXECUTE query;
EXECUTE 'FETCH NEXT FROM '||cursorname;
-- for test development
-- RAISE NOTICE '%: %', cursorname, query;
END LOOP;
END;
$f$;
-- Test overflow of temp table buffers is handled correctly
BEGIN;
-- should work, below max
SELECT test_temp_pin(0, 9);
-- should fail, too many buffers pinned
SELECT test_temp_pin(10, 105);
ROLLBACK;
BEGIN;
-- have some working cursors to test after errors
SELECT test_temp_pin(0, 9);
FETCH NEXT FROM c_3;
-- exhaust buffer pins in subtrans, check things work after
SAVEPOINT rescue_me;
SELECT test_temp_pin(10, 105);
ROLLBACK TO SAVEPOINT rescue_me;
-- pre-subtrans cursors continue to work
FETCH NEXT FROM c_3;
-- new cursors with pins can be created after subtrans rollback
SELECT test_temp_pin(10, 94);
-- Check that read streams deal with lower number of pins available
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
ROLLBACK;
-- Check that temp tables with existing cursors can't be dropped.
BEGIN;
SELECT test_temp_pin(0, 1);
DROP TABLE test_temp;
COMMIT;
-- Check that temp tables with existing cursors can't be dropped.
BEGIN;
SELECT test_temp_pin(0, 1);
TRUNCATE test_temp;
COMMIT;
-- Check that temp tables that are dropped in transaction that's rolled back
-- preserve buffer contents
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
INSERT INTO test_temp(a, b, cnt) VALUES (-1, '', 0);
BEGIN;
INSERT INTO test_temp(a, b, cnt) VALUES (-2, '', 0);
DROP TABLE test_temp;
ROLLBACK;
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
-- Check that temp table drop is transactional and preserves dirty
-- buffer contents
UPDATE test_temp SET cnt = cnt + 1 WHERE a = -1;
BEGIN;
DROP TABLE test_temp;
ROLLBACK;
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
-- Check that temp table truncation is transactional and preserves dirty
-- buffer contents
UPDATE test_temp SET cnt = cnt + 1 WHERE a = -1;
BEGIN;
TRUNCATE test_temp;
ROLLBACK;
SELECT count(*), max(a) max_a, min(a) min_a, max(cnt) max_cnt FROM test_temp;
-- cleanup
DROP FUNCTION test_temp_pin(int, int);