Doc: mention that VACUUM can't utilize over 1GB of RAM

Document that setting maintenance_work_mem to values over 1GB has no
effect on VACUUM.

Reported-by: Martín Marqués
Author: Laurenz Albe
Discussion: https://postgr.es/m/CABeG9LsZ2ozUMcqtqWu_-GiFKB17ih3p8wBHXcpfnHqhCnsc7A%40mail.gmail.com
Backpatch-through: 9.6, oldest supported release

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3eee9883595ff2eca518893d375f526f6e46657f..1bbc631afe5df887dfa285d87d217bc138a9527e 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1893,6 +1893,12 @@ include_dir 'conf.d'
         too high.  It may be useful to control for this by separately
         setting .
        
+       
+        Additionally, VACUUM is only able to utilize up to
+        a maximum of 1GB of memory, so
+        maintenance_work_mem values higher than this have
+        no effect on VACUUM.
+