postgres.git / summary / log / commit / refs
commit aa7d0b6cf954c53e9e7f446c9cd75761013d6f35
Author: Bruce Momjian <bruce@momjian.us>
Date: Tue Sep 26 23:44:21 2023 +0000
doc: clarify the effect of concurrent work_mem allocations
Reported-by: Sami Imseih
Discussion: https://postgr.es/m/66590882-F48C-4A25-83E3-73792CF8C51F@amazon.com
Backpatch-through: 11
doc/src/sgml/config.sgml | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index ddd78beec8d..186f870fc75 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1815,9 +1815,10 @@ include_dir 'conf.d'
(such as a sort or hash table) before writing to temporary disk files.
If this value is specified without units, it is taken as kilobytes.
The default value is four megabytes (<literal>4MB</literal>).
- Note that for a complex query, several sort or hash operations might be
- running in parallel; each operation will generally be allowed
- to use as much memory as this value specifies before it starts
+ Note that a complex query might perform several sort and hash
+ operations at the same time, with each operation generally being
+ allowed to use as much memory as this value specifies before
+ it starts
to write data into temporary files. Also, several running
sessions could be doing such operations concurrently.
Therefore, the total memory used could be many times the value
@@ -1831,7 +1832,7 @@ include_dir 'conf.d'
<para>
Hash-based operations are generally more sensitive to memory
availability than equivalent sort-based operations. The
- memory available for hash tables is computed by multiplying
+ memory limit for a hash table is computed by multiplying
<varname>work_mem</varname> by
<varname>hash_mem_multiplier</varname>. This makes it
possible for hash-based operations to use an amount of memory
[parent: 587a3563cbb5]