Re: tds_fdw : Severe performance degradation from postgresql 10.23 to 16.4 - Mailing list pgsql-performance

From Tom Lane
Subject Re: tds_fdw : Severe performance degradation from postgresql 10.23 to 16.4
Date
Msg-id 1224347.1731440256@sss.pgh.pa.us
Whole thread Raw
In response to Re: tds_fdw : Severe performance degradation from postgresql 10.23 to 16.4  (Achilleas Mantzios <a.mantzios@cloud.gatewaynet.com>)
Responses Re: tds_fdw : Severe performance degradation from postgresql 10.23 to 16.4
Re: tds_fdw : Severe performance degradation from postgresql 10.23 to 16.4
List pgsql-performance
Achilleas Mantzios <a.mantzios@cloud.gatewaynet.com> writes:
> Our sysadm created the system debian Debian GNU/Linux 12 (bookworm)with 
> postgres as user 1000. Now at some point we realized that whenever we 
> run a pgsql cluster with another user (I found that after spending two 
> good days testing), the above query runs in about 1 second. With user 
> postgres 1000 in 30 seconds. As you saw the perf output are completely 
> different.

Don't recall details offhand, but in some situations where the calling
SQL user doesn't have permissions to read particular columns, the
planner will not consult statistics for those columns.  That can lead
to a different, less optimal plan being used.  Maybe something like
that is happening here?

            regards, tom lane



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