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doc: improve text around consistency of statistics values

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Discussion: https://postgr.es/m/CAKFQuwZ4CXtTyR19vFbd9WwmW-4BvgAenmF2CfUpx0LWwRPGYg@mail.gmail.com

Author: David G. Johnston

Backpatch-through: master
This commit is contained in:
Bruce Momjian 2023-10-27 21:24:55 -04:00
parent eb544d7fd9
commit 05ce730978
1 changed files with 3 additions and 4 deletions
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doc/src/sgml/maintenance.sgml
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@ -924,10 +924,9 @@ vacuum insert threshold = vacuum base insert threshold + vacuum insert scale fac
<xref linkend="reloption-autovacuum-freeze-min-age"/> as this may allow <xref linkend="reloption-autovacuum-freeze-min-age"/> as this may allow
tuples to be frozen by earlier vacuums. The number of obsolete tuples and tuples to be frozen by earlier vacuums. The number of obsolete tuples and
the number of inserted tuples are obtained from the cumulative statistics system; the number of inserted tuples are obtained from the cumulative statistics system;
it is a semi-accurate count updated by each <command>UPDATE</command>, it is an eventually-consistent count updated by each <command>UPDATE</command>,
<command>DELETE</command> and <command>INSERT</command> operation. (It is <command>DELETE</command> and <command>INSERT</command> operation.
only semi-accurate because some information might be lost under heavy If the <structfield>relfrozenxid</structfield> value of the table
load.) If the <structfield>relfrozenxid</structfield> value of the table
is more than <varname>vacuum_freeze_table_age</varname> transactions old, is more than <varname>vacuum_freeze_table_age</varname> transactions old,
an aggressive vacuum is performed to freeze old tuples and advance an aggressive vacuum is performed to freeze old tuples and advance
<structfield>relfrozenxid</structfield>; otherwise, only pages that have been modified <structfield>relfrozenxid</structfield>; otherwise, only pages that have been modified