doc: clarify the effect of concurrent work_mem allocations

bmomjian · bmomjian · commit a4a8c0de2b81 · 2023-09-26T19:44:21.000-04:00
Reported-by: Sami Imseih Discussion: https://postgr.es/m/66590882-F48C-4A25-83E3-73792CF8C51F@amazon.com Backpatch-through: 11
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
@@ -1582,9 +1582,10 @@ include_dir 'conf.d'
         Specifies the amount of memory to be used by internal sort operations
         and hash tables before writing to temporary disk files. The value
         defaults to four megabytes (<literal>4MB</literal>).
-        Note that for a complex query, several sort or hash operations might be
-        running in parallel; each operation will be allowed to use as much memory
-        as this value specifies before it starts to write data into temporary
+        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 of <varname>work_mem</varname>; it is necessary to
