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pg_surgery: Try to stabilize regression tests.

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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 a7212be8b9e0885ee769e8c55f99ef742cda487b 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
This commit is contained in:
Robert Haas 2020-09-18 13:26:48 -04:00
parent 24fb35e111
commit 0811f766fd
2 changed files with 8 additions and 13 deletions
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10
contrib/pg_surgery/expected/heap_surgery.out
View File

@ -1,8 +1,7 @@
create extension pg_surgery;
-- create a normal heap table and insert some rows.
-- note that we don't commit the transaction, so autovacuum can't interfere.
begin;
create table htab(a int);
-- 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[]);
@ -85,9 +84,9 @@ NOTICE: skipping tid (0, 6) for relation "htab" because the item number is out
(1 row)
rollback;
-- set up a new table with a redirected line pointer
create table htab2(a int) with (autovacuum_enabled = off);
-- 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;
@ -175,6 +174,5 @@ ERROR: "vw" is not a table, materialized view, or TOAST table
select heap_force_freeze('vw'::regclass, ARRAY['(0, 1)']::tid[]);
ERROR: "vw" is not a table, materialized view, or TOAST table
-- cleanup.
drop table htab2;
drop view vw;
drop extension pg_surgery;

11
contrib/pg_surgery/sql/heap_surgery.sql
View File

@ -1,9 +1,8 @@
create extension pg_surgery;
-- create a normal heap table and insert some rows.
-- note that we don't commit the transaction, so autovacuum can't interfere.
begin;
create table htab(a int);
-- 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
@ -38,10 +37,9 @@ 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[]);
rollback;
-- set up a new table with a redirected line pointer
create table htab2(a int) with (autovacuum_enabled = off);
-- 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;
@ -86,6 +84,5 @@ select heap_force_kill('vw'::regclass, ARRAY['(0, 1)']::tid[]);
select heap_force_freeze('vw'::regclass, ARRAY['(0, 1)']::tid[]);
-- cleanup.
drop table htab2;
drop view vw;
drop extension pg_surgery;