digoal
2023-03-06
PostgreSQL , PolarDB , vacuum , PROCESS_MAIN , PROCESS_TOAST
vacuum 支持通过 PROCESS_MAIN, PROCESS_TOAST 来配置是否处理“主存储”或“toast存储”.
VACUUM (PROCESS_MAIN FALSE, PROCESS_TOAST FALSE) vac_option_tab;
Add PROCESS_MAIN to VACUUM master github/master
author Michael Paquier <michael@paquier.xyz>
Mon, 6 Mar 2023 07:41:05 +0000 (16:41 +0900)
committer Michael Paquier <michael@paquier.xyz>
Mon, 6 Mar 2023 07:41:05 +0000 (16:41 +0900)
commit 4211fbd8413b26e0abedbe4338aa7cda2cd469b4
tree 0c8ac21d9f1a3c83463e79da5e104153741c86e4 tree
parent 46d490ac19a7ca93a5c0f47e5a0e759b5385a8ae commit | diff
Add PROCESS_MAIN to VACUUM
Disabling this option is useful to run VACUUM (with or without FULL) on
only the toast table of a relation, bypassing the main relation. This
option is enabled by default.
Running directly VACUUM on a toast table was already possible without
this feature, by using the non-deterministic name of a toast relation
(as of pg_toast.pg_toast_N, where N would be the OID of the parent
relation) in the VACUUM command, and it required a scan of pg_class to
know the name of the toast table. So this feature is basically a
shortcut to be able to run VACUUM or VACUUM FULL on a toast relation,
using only the name of the parent relation.
A new switch called --no-process-main is added to vacuumdb, to work as
an equivalent of PROCESS_MAIN.
Regression tests are added to cover VACUUM and VACUUM FULL, looking at
pg_stat_all_tables.vacuum_count to see how many vacuums have run on
each table, main or toast.
Author: Nathan Bossart
Reviewed-by: Masahiko Sawada
Discussion: https://postgr.es/m/20221230000028.GA435655@nathanxps13
+-- PROCESS_MAIN option
+-- Only the toast table is processed.
+VACUUM (PROCESS_MAIN FALSE) vac_option_tab;
+SELECT * FROM vac_option_tab_counts;
+ rel | vacuum_count
+-------+--------------
+ main | 2
+ toast | 2
+(2 rows)
+
+-- Nothing is processed.
+VACUUM (PROCESS_MAIN FALSE, PROCESS_TOAST FALSE) vac_option_tab;
+SELECT * FROM vac_option_tab_counts;
+ rel | vacuum_count
+-------+--------------
+ main | 2
+ toast | 2
+(2 rows)
