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| author | Bruce Momjian <bruce@momjian.us> | 2009-04-10 03:13:36 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2009-04-10 03:13:36 +0000 |
| commit | 51781146a8307c18f4ee74dbe8c780910f3287b9 (patch) | |
| tree | 5153e0698cd59f60b09def770c9648cdcc4fb954 | |
| parent | 4c9c0b85fb9d5255f9e936ec2effe112dcb8a99c (diff) | |
Document how *_blks_read statistics columns are computed.
| -rw-r--r-- | doc/src/sgml/monitoring.sgml | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index acfccc4c997..8c4f2b7db1a 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.67 2009/04/09 22:32:02 momjian Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.68 2009/04/10 03:13:36 momjian Exp $ --> <chapter id="monitoring"> <title>Monitoring Database Activity</title> @@ -927,8 +927,9 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re <function>pg_stat_get_blocks_fetched</function> minus <function>pg_stat_get_blocks_hit</function> gives the number of kernel <function>read()</> calls issued for the table, index, or - database; but the actual number of physical reads is usually - lower due to kernel-level buffering. + database; the number of actual physical reads is usually + lower due to kernel-level buffering. The <literal>*_blks_read</> + statistics columns uses this subtraction, i.e. fetched minus hit. </para> </note> |