Re: monitoring-stats.html documentation

Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > http://developer.postgresql.org/pgdocs/postgres/monitoring-stats.html
> > says: "Note: blocks_fetched minus blocks_hit gives the number of
> > kernel read() calls issued for the table, index, or database; but the
> > actual number of physical reads is usually lower due to kernel-level
> > buffering." This seems to imply that anything that increases
> > blocks_hit should also increase blocks_fetched, but that doesn't seem
> > to match the actual behavior.
>
> > rhaas=# select heap_blks_read, heap_blks_hit from pg_statio_user_tables;
>
> It's talking about the underlying pg_stat_get_db_blocks_fetched()
> function, not heap_blks_read which is just a view field defined as
>
> pg_stat_get_blocks_fetched(C.oid) -
> pg_stat_get_blocks_hit(C.oid) AS heap_blks_read,
>
> Probably that sentence ought to spell out the full function name
> instead of abbreviating.

Done.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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