Doc: enhance query cache doc.

Pgpool refuses to cache a query calling functions returning TIMESTAMP
WITH TIMEZONE, TIME WITH TIMEZONE. If there are multiple functions
having same name and one of them returns TIMESTAMP WITH TIMEZONE, TIME
WITH TIMEZONE, pgpool refuses to cache even if one of them does not
return the data types. So add a note on this along with workaround.

1 files changed, 13 insertions, 0 deletions

diff --git a/doc/src/sgml/memcache.sgml b/doc/src/sgml/memcache.sgml
index 6cd920531..b1a48ed7d 100644
--- a/doc/src/sgml/memcache.sgml
+++ b/doc/src/sgml/memcache.sgml
@@ -99,6 +99,19 @@
   </para>
  </note>
 
+ <note>
+  <para>
+   If multiple functions having the same name are registered and one
+   of them returns TIMESTAMP WITH TIMEZONE or TIME WITH
+   TIMEZONE, <productname>Pgpool-II</productname> thinks that the
+   query cannot be cached even if it uses a version of function which
+   does not return TIMESTAMP WITH TIMEZONE or TIME WITH TIMEZONE. In
+   this case you can create a wrapper function returning TIMESTAMP
+   WITHOUT TIMEZONE or TIME WITHOUT TIMEZONE, or use /*FORCE QUERY
+   CACHE*/ comment so that you can use the query cache.
+  </para>
+ </note>
+
  <para>
   On the other hand, it might be slower than the normal path
   in some cases, because it adds some overhead to store cache.