diff options
| author | Nathan Bossart <nathan@postgresql.org> | 2025-11-19 10:01:37 -0600 |
|---|---|---|
| committer | Nathan Bossart <nathan@postgresql.org> | 2025-11-19 10:01:37 -0600 |
| commit | cbdce71b9984e9bb2d8b3a4a8de466cbb2c32ea7 (patch) | |
| tree | 586b848513afae11a55985e2f7f1dc141793363b | |
| parent | 86b276a4a9b4b2c63ef00765f0e2867e1bcac4ca (diff) | |
doc: Update formula for vacuum insert threshold.
Oversight in commit 06eae9e621.
Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Discussion: https://postgr.es/m/aRODeqFUVkGDJSPP%40nathan
Backpatch-through: 18
| -rw-r--r-- | doc/src/sgml/maintenance.sgml | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml index 120bac8875f..f4f0433ef6f 100644 --- a/doc/src/sgml/maintenance.sgml +++ b/doc/src/sgml/maintenance.sgml @@ -934,12 +934,16 @@ vacuum threshold = Minimum(vacuum max threshold, vacuum base threshold + vacuum The table is also vacuumed if the number of tuples inserted since the last vacuum has exceeded the defined insert threshold, which is defined as: <programlisting> -vacuum insert threshold = vacuum base insert threshold + vacuum insert scale factor * number of tuples +vacuum insert threshold = vacuum base insert threshold + vacuum insert scale factor * number of tuples * percent of table not frozen </programlisting> where the vacuum insert base threshold is <xref linkend="guc-autovacuum-vacuum-insert-threshold"/>, - and vacuum insert scale factor is - <xref linkend="guc-autovacuum-vacuum-insert-scale-factor"/>. + the vacuum insert scale factor is + <xref linkend="guc-autovacuum-vacuum-insert-scale-factor"/>, + the number of tuples is + <structname>pg_class</structname>.<structfield>reltuples</structfield>, + and the percent of the table not frozen is + <literal>1 - pg_class.relallfrozen / pg_class.relpages</literal>. Such vacuums may allow portions of the table to be marked as <firstterm>all visible</firstterm> and also allow tuples to be frozen, which can reduce the work required in subsequent vacuums. |