Thread: pg_stat

pg_stat

From
Litao Wu
Date:
Hi,

I have query:
select pg_stat_get_numscans(76529669),
pg_stat_get_blocks_fetched(76529669),
pg_stat_get_blocks_hit(76529669);

The result is:
 pg_stat_get_numscans | pg_stat_get_blocks_fetched |
pg_stat_get_blocks_hit
----------------------+----------------------------+------------------------
                    0 |                      23617 |
               23595
(1 row)

My questions are:
1. How can index disk blocks be requested (either
from disk or cache) without index scan?
2. If I want to check if an index is used after
pg_stat_reset(), how can I get it? By number of scans
or block requests, or some other ways?

Thanks,




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Re: pg_stat

From
Litao Wu
Date:
All,

Since I have not seen any follow up post,
I am wondering if my question is not clear or
what.

Anyway, my postgres version is 7.3.2, and I
want to know:
1. How to determine if some of indexes are used by
any queries, like Oracle's:
alter index my_index monitoring usage
2. The relationship between
"number of index scans done" and
"Number of disk block fetch requests for index"
as shown in the query.

Thank you!

--- Litao Wu <litaowu@yahoo.com> wrote:
> Hi,
>
> I have query:
> select pg_stat_get_numscans(76529669),
> pg_stat_get_blocks_fetched(76529669),
> pg_stat_get_blocks_hit(76529669);
>
> The result is:
>  pg_stat_get_numscans | pg_stat_get_blocks_fetched |
> pg_stat_get_blocks_hit
>
----------------------+----------------------------+------------------------
>                     0 |                      23617 |
>
>                23595
> (1 row)
>
> My questions are:
> 1. How can index disk blocks be requested (either
> from disk or cache) without index scan?
> 2. If I want to check if an index is used after
> pg_stat_reset(), how can I get it? By number of
> scans
> or block requests, or some other ways?
>
> Thanks,
>
>
>
>
> __________________________________
> Do you Yahoo!?
> Win a $20,000 Career Makeover at Yahoo! HotJobs
> http://hotjobs.sweepstakes.yahoo.com/careermakeover
>





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