doc: Add note about checkpoint_warning vs checkpoint_timeout

suggested by Tianyin Xu

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 175d1d5ebf4e79eb57953aa11313763aea3cf87c..ae6ee60ab16370d11666d6f5e0d728fc1d40231d 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2057,6 +2057,8 @@ include 'filename'
         than this many seconds (which suggests that
         <varname>checkpoint_segments</> ought to be raised).  The default is
         30 seconds (<literal>30s</>).  Zero disables the warning.
+        No warnings will be generated if <varname>checkpoint_timeout</varname>
+        is less than <varname>checkpoint_warning</varname>.
         This parameter can only be set in the <filename>postgresql.conf</>
         file or on the server command line.
        </para>