postgresql/contrib/pg_surgery/sql/heap_surgery.sql
Robert Haas 0811f766fd pg_surgery: Try to stabilize regression tests.
According to buildfarm member sungazer, the behavior of VACUUM can be
unstable in these tests even if we prevent autovacuum from running on
the tables in question, apparently because even a manual vacuum can
behave differently depending on whether anything else is running that
holds back the global xmin. So use a temporary table instead, which
as of commit a7212be8b9 enables
vacuuming using a more aggressive cutoff.

This approach can't be used for the regression test that involves a
materialized view, but that test doesn't run vacuum, so it shouldn't
be prone to this particular failure mode.

Analysis by Tom Lane. Patch by Ashutosh Sharma and me.

Discussion: http://postgr.es/m/665524.1599948007@sss.pgh.pa.us
2020-09-18 13:26:48 -04:00

89 lines
2.8 KiB
PL/PgSQL

create extension pg_surgery;
-- create a normal heap table and insert some rows.
-- use a temp table so that vacuum behavior doesn't depend on global xmin
create temp table htab (a int);
insert into htab values (100), (200), (300), (400), (500);
-- test empty TID array
select heap_force_freeze('htab'::regclass, ARRAY[]::tid[]);
-- nothing should be frozen yet
select * from htab where xmin = 2;
-- freeze forcibly
select heap_force_freeze('htab'::regclass, ARRAY['(0, 4)']::tid[]);
-- now we should have one frozen tuple
select ctid, xmax from htab where xmin = 2;
-- kill forcibly
select heap_force_kill('htab'::regclass, ARRAY['(0, 4)']::tid[]);
-- should be gone now
select * from htab where ctid = '(0, 4)';
-- should now be skipped because it's already dead
select heap_force_kill('htab'::regclass, ARRAY['(0, 4)']::tid[]);
select heap_force_freeze('htab'::regclass, ARRAY['(0, 4)']::tid[]);
-- freeze two TIDs at once while skipping an out-of-range block number
select heap_force_freeze('htab'::regclass,
ARRAY['(0, 1)', '(0, 3)', '(1, 1)']::tid[]);
-- we should now have two frozen tuples
select ctid, xmax from htab where xmin = 2;
-- out-of-range TIDs should be skipped
select heap_force_freeze('htab'::regclass, ARRAY['(0, 0)', '(0, 6)']::tid[]);
-- set up a new table with a redirected line pointer
-- use a temp table so that vacuum behavior doesn't depend on global xmin
create temp table htab2(a int);
insert into htab2 values (100);
update htab2 set a = 200;
vacuum htab2;
-- redirected TIDs should be skipped
select heap_force_kill('htab2'::regclass, ARRAY['(0, 1)']::tid[]);
-- now create an unused line pointer
select ctid from htab2;
update htab2 set a = 300;
select ctid from htab2;
vacuum freeze htab2;
-- unused TIDs should be skipped
select heap_force_kill('htab2'::regclass, ARRAY['(0, 2)']::tid[]);
-- multidimensional TID array should be rejected
select heap_force_kill('htab2'::regclass, ARRAY[['(0, 2)']]::tid[]);
-- TID array with nulls should be rejected
select heap_force_kill('htab2'::regclass, ARRAY[NULL]::tid[]);
-- but we should be able to kill the one tuple we have
select heap_force_kill('htab2'::regclass, ARRAY['(0, 3)']::tid[]);
-- materialized view.
-- note that we don't commit the transaction, so autovacuum can't interfere.
begin;
create materialized view mvw as select a from generate_series(1, 3) a;
select * from mvw where xmin = 2;
select heap_force_freeze('mvw'::regclass, ARRAY['(0, 3)']::tid[]);
select * from mvw where xmin = 2;
select heap_force_kill('mvw'::regclass, ARRAY['(0, 3)']::tid[]);
select * from mvw where ctid = '(0, 3)';
rollback;
-- check that it fails on an unsupported relkind
create view vw as select 1;
select heap_force_kill('vw'::regclass, ARRAY['(0, 1)']::tid[]);
select heap_force_freeze('vw'::regclass, ARRAY['(0, 1)']::tid[]);
-- cleanup.
drop view vw;
drop extension pg_surgery;