More buffers used than a relation's relpages - Mailing list pgsql-general

Hello,

In what cases can a relation use more buffers (in shared memory) than
its pg_class.relpages?

For example, look at the second row in the following:

postgres=# SELECT c.relname,count(*) AS buffers, c.relpages
FROM pg_class c INNER JOIN pg_buffercache b
ON b.relfilenode=c.relfilenode INNER JOIN pg_database d
ON (b.reldatabase=d.oid AND d.datname=current_database())
GROUP BY c.relname,c.relpages
ORDER BY 2 DESC;
              relname              | buffers | relpages
-----------------------------------+---------+----------
 abc_idx          |    4800 |     4800
 abc                             |    3548 |     3547
abc_2_idx                |    3209 |     3209
...
...



--
Amit Langote