Обсуждение: pg_statio_all_indexes

Hi, I'm not sure about the value idx_blks_hit of pg_statio_all_indexes
view. Is it total value of touched pages, or do I get total value when
I add idx_blks_read to it?
In other words - does idx_blks_hit cover also physical reads?

Thanks,
       David Hoksza

As per my understanding, 'pg_statio_all_indexes' displays "idx_blks_hit" using "pg_stat_get_blocks_hit(oid)" where the function "pg_stat_get_blocks_hit" gets number of disk block requests found in cache for a table or index.

Hope this helps...

Thanks,
 --
Shoaib Mir
EnterpriseDB (www.enterprisedb.com)

David Hoksza <david.hoksza@seznam.cz> writes:
> Hi, I'm not sure about the value idx_blks_hit of pg_statio_all_indexes
> view. Is it total value of touched pages, or do I get total value when
> I add idx_blks_read to it?
> In other words - does idx_blks_hit cover also physical reads?

I believe blks_hit is the number of page requests that were found in
cache and hence did *not* require a read().  The other column is the
number of page requests that *did* require a read().

            regards, tom lane

Yes, you are right. I now tried to select from one table various amount of
records and when the amount exceeded some given number so the blks_hit begun
fall.

Thanks,
       David Hoksza

________________________________
30. července 2006, 20:24:33, napsal jste:

TL> David Hoksza <david.hoksza@seznam.cz> writes:
>> Hi, I'm not sure about the value idx_blks_hit of pg_statio_all_indexes
>> view. Is it total value of touched pages, or do I get total value when
>> I add idx_blks_read to it?
>> In other words - does idx_blks_hit cover also physical reads?

TL> I believe blks_hit is the number of page requests that were found in
TL> cache and hence did *not* require a read().  The other column is the
TL> number of page requests that *did* require a read().

TL>                         regards, tom lane