postgres.git / summary / log / commit / refs

commit    bb08e78972b1d0ec9f11f3d0b18903ec7a216855
Author:   David Rowley <drowley@postgresql.org>
Date:     Mon Aug 09 04:47:25 2021 +0000
First released in: 15.0, 9.6.23, 10.18, 11.13, 12.8, 13.4, 14.0

    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


 doc/src/sgml/config.sgml | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 752697f07f0..92ac53f9a5e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1770,10 +1770,9 @@ 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>
@@ -1797,6 +1796,13 @@ 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>
 


[parent: ff18b8d1b169]