From 26dac7d2d9768c072913c911776d4f679bb21126 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Thu, 16 Jan 2025 16:31:55 -0500 Subject: [PATCH v7 2/2] Trigger more frequent autovacuums with relallfrozen Calculate the insert threshold for triggering an autovacuum of a relation based on the number of unfrozen pages. By only considering the "active" (unfrozen) portion of the table when calculating how many tuples to add to the insert threshold, we can trigger more frequent vacuums of insert-heavy tables and increase the chances of vacuuming those pages when they still reside in shared buffers. Reviewed-by: Greg Sabino Mullane --- doc/src/sgml/config.sgml | 16 +++++------ src/backend/postmaster/autovacuum.c | 27 ++++++++++++++++--- src/backend/utils/misc/postgresql.conf.sample | 4 +-- 3 files changed, 34 insertions(+), 13 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 007746a4429..cdd477e62c3 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -8767,14 +8767,14 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; - Specifies a fraction of the table size to add to - autovacuum_vacuum_insert_threshold - when deciding whether to trigger a VACUUM. - The default is 0.2 (20% of table size). - This parameter can only be set in the postgresql.conf - file or on the server command line; - but the setting can be overridden for individual tables by - changing table storage parameters. + Specifies a fraction of the active (unfrozen) table size to add to + autovacuum_vacuum_insert_threshold + when deciding whether to trigger a VACUUM. + The default is 0.2 (20% of active table size). + This parameter can only be set in the postgresql.conf + file or on the server command line; + but the setting can be overridden for individual tables by + changing table storage parameters. diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c index ade2708b59e..050dbd43a22 100644 --- a/src/backend/postmaster/autovacuum.c +++ b/src/backend/postmaster/autovacuum.c @@ -2938,7 +2938,6 @@ relation_needs_vacanalyze(Oid relid, { bool force_vacuum; bool av_enabled; - float4 reltuples; /* pg_class.reltuples */ /* constants from reloptions or GUC variables */ int vac_base_thresh, @@ -3052,7 +3051,11 @@ relation_needs_vacanalyze(Oid relid, */ if (PointerIsValid(tabentry) && AutoVacuumingActive()) { - reltuples = classForm->reltuples; + float4 pcnt_unfrozen = 1; + float4 reltuples = classForm->reltuples; + int32 relpages = classForm->relpages; + int32 relallfrozen = classForm->relallfrozen; + vactuples = tabentry->dead_tuples; instuples = tabentry->ins_since_vacuum; anltuples = tabentry->mod_since_analyze; @@ -3061,11 +3064,29 @@ relation_needs_vacanalyze(Oid relid, if (reltuples < 0) reltuples = 0; + /* + * If we have data for relallfrozen, calculate the unfrozen percentage + * of the table to modify insert scale factor. This helps us decide + * whether or not to vacuum an insert-heavy table based on the number + * of inserts to the "active" part of the table. + */ + if (relpages > 0 && relallfrozen > 0) + { + /* + * It could be the stats were updated manually and relallfrozen > + * relpages. Clamp relallfrozen to relpages to avoid nonsensical + * calculations. + */ + relallfrozen = Min(relallfrozen, relpages); + pcnt_unfrozen = 1 - ((float4) relallfrozen / relpages); + } + vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples; if (vac_max_thresh >= 0 && vacthresh > (float4) vac_max_thresh) vacthresh = (float4) vac_max_thresh; - vacinsthresh = (float4) vac_ins_base_thresh + vac_ins_scale_factor * reltuples; + vacinsthresh = (float4) vac_ins_base_thresh + + vac_ins_scale_factor * reltuples * pcnt_unfrozen; anlthresh = (float4) anl_base_thresh + anl_scale_factor * reltuples; /* diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 5362ff80519..acf45efc4ba 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -675,8 +675,8 @@ autovacuum_worker_slots = 16 # autovacuum worker slots to allocate #autovacuum_analyze_threshold = 50 # min number of row updates before # analyze #autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum -#autovacuum_vacuum_insert_scale_factor = 0.2 # fraction of inserts over table - # size before insert vacuum +#autovacuum_vacuum_insert_scale_factor = 0.2 # fraction of inserts over active + # table size before insert vacuum #autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze #autovacuum_vacuum_max_threshold = 100000000 # max number of row updates # before vacuum; -1 disables max -- 2.34.1