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| author | David Rowley <drowley@postgresql.org> | 2021-08-09 16:48:37 +1200 |
|---|---|---|
| committer | David Rowley <drowley@postgresql.org> | 2021-08-09 16:48:37 +1200 |
| commit | 6df2971d32803c44d671d3a93fc718cb82fd7883 (patch) | |
| tree | e7b711d838ad60acd6338683440afe15efd1dd31 | |
| parent | cfb70a120bbac4b197aabc663e1400c3cb599ffe (diff) | |
| download | postgresql-6df2971d32803c44d671d3a93fc718cb82fd7883.tar.gz postgresql-6df2971d32803c44d671d3a93fc718cb82fd7883.zip | |
Doc: Fix misleading statement about VACUUM memory limits
In ec34040af I added a mention that there was no point in setting
maintenance_work_limit to anything higher than 1GB for vacuum, but that
was incorrect as ginInsertCleanup() also looks at what
maintenance_work_mem is set to during VACUUM and that's not limited to
1GB.
Here I attempt to make it more clear that the limitation is only around
the number of dead tuple identifiers that we can collect during VACUUM.
I've also added a note to autovacuum_work_mem to mention this limitation.
I didn't do that in ec34040af as I'd had some wrong-headed ideas about
just limiting the maximum value for that GUC to 1GB.
Author: David Rowley
Discussion: https://postgr.es/m/CAApHDvpGwOAvunp-E-bN_rbAs3hmxMoasm5pzkYDbf36h73s7w@mail.gmail.com
Backpatch-through: 9.6, same as ec34040af
| -rw-r--r-- | doc/src/sgml/config.sgml | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 32c8fb8ea92..e500b1fdecc 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1618,10 +1618,9 @@ include_dir 'conf.d' setting <xref linkend="guc-autovacuum-work-mem"/>. </para> <para> - Additionally, <command>VACUUM</command> is only able to utilize up to - a maximum of <literal>1GB</literal> of memory, so - <varname>maintenance_work_mem</varname> values higher than this have - no effect on <command>VACUUM</command>. + Note that for the collection of dead tuple identifiers, + <command>VACUUM</command> is only able to utilize up to a maximum of + <literal>1GB</literal> of memory. </para> </listitem> </varlistentry> @@ -1643,6 +1642,13 @@ include_dir 'conf.d' <filename>postgresql.conf</filename> file or on the server command line. </para> + <para> + For the collection of dead tuple identifiers, autovacuum is only able + to utilize up to a maximum of <literal>1GB</literal> of memory, so + setting <varname>autovacuum_work_mem</varname> to a value higher than + that has no effect on the number of dead tuples that autovacuum can + collect while scanning a table. + </para> </listitem> </varlistentry> |