From f57791985ac3d776cb67e9d69befde538cfdf13b Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Fri, 22 Aug 2014 00:28:37 +0200
Subject: Add pinning_backends column to the pg_buffercache extension.

The new column shows how many backends have a buffer pinned. That can
be useful during development or to diagnose production issues
e.g. caused by vacuum waiting for cleanup locks.

To handle upgrades transparently - the extension might be used in
views - deal with callers expecting the old number of columns.

Reviewed by Fujii Masao and Rajeev rastogi.
---
 doc/src/sgml/pgbuffercache.sgml | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'doc/src')

diff --git a/doc/src/sgml/pgbuffercache.sgml b/doc/src/sgml/pgbuffercache.sgml
index 4eb02c06239..f379be225f0 100644
--- a/doc/src/sgml/pgbuffercache.sgml
+++ b/doc/src/sgml/pgbuffercache.sgml
@@ -106,6 +106,13 @@
       <entry>Clock-sweep access count</entry>
      </row>
 
+     <row>
+      <entry><structfield>pinning_backends</structfield></entry>
+      <entry><type>integer</type></entry>
+      <entry></entry>
+      <entry>Number of backends pinning this buffer</entry>
+     </row>
+
     </tbody>
    </tgroup>
   </table>
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