Re: Support reset of Shared objects statistics in "pg_stat_reset" function

Hi Sadhu,

> The call to “pg_stat_reset“ does reset all the statistics data for
> tables belonging to the current database but does not take care of
> shared tables e.g pg_attribute.

pg_attribute is not a shared catalog, is the mentioned scenario is also
applicable for few others tables?

I have just tried it with-out your patch:

postgres=# SELECT * FROM pg_statio_all_tables where relid=1249;
relid | schemaname | relname | heap_blks_read | heap_blks_hit |
idx_blks_read | idx_blks_hit | toast_blks_read | toast_blks_hit |
tidx_blks_read | tidx_blks_hit
-------+------------+--------------+----------------+---------------+---------------+--------------+-----------------+----------------+----------------+---------------
1249 | pg_catalog | pg_attribute | 29 | 522 |
8 | 673 | | |
|
(1 row)

postgres=# select pg_stat_reset();
pg_stat_reset
---------------

(1 row)

postgres=# SELECT * FROM pg_statio_all_tables where relid=1249;
relid | schemaname | relname | heap_blks_read | heap_blks_hit |
idx_blks_read | idx_blks_hit | toast_blks_read | toast_blks_hit |
tidx_blks_read | tidx_blks_hit
-------+------------+--------------+----------------+---------------+---------------+--------------+-----------------+----------------+----------------+---------------
1249 | pg_catalog | pg_attribute | 0 | 0 |
0 | 0 | | |
|

We are able to reset the stats of pg_attibute without your patch.

Thanks,
Himanshu

On Fri, Aug 6, 2021 at 1:56 PM Sadhuprasad Patro <b(dot)sadhu(at)gmail(dot)com> wrote:

> Hi,
>
> The call to “pg_stat_reset“ does reset all the statistics data for
> tables belonging to the current database but does not take care of
> shared tables e.g pg_attribute. Similarly to reset the statistics at
> table level, the call to “pg_stat_reset_single_table_counters“ does
> not take care of shared tables.
>
> When we reset all the statistics using the call “pg_stat_reset”, the
> postgres process internally makes calls to “
> pgstat_recv_resetcounter“, which resets the statistics of all the
> tables of the current database. But not resetting the statistics of
> shared objects using database ID as 'InvalidOid'.
>
> The same fix is made in the internal function
> “pgstat_recv_resetsinglecounter“ to reset the statistics for the
> shared table for the call "pg_stat_reset_single_table_counters".
>
> --
> thank u
> SADHU PRASAD
> EnterpriseDB: http://www.enterprisedb.com
>