Re: tds_fdw : Severe performance degradation from postgresql 10.23 to 16.4

On 11/12/24 21:37, Tom Lane wrote:
> 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?

Thank you Tom,

In all runs of this query the user is postgres (superuser). Besides, 
this is just a simple query run on a FOREIGN TABLE living in a MS SQL 
Server.

>
>             regards, tom lane