Re: Simple query with Planner underestimating rows.

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On 1/29/25 15:32, Felipe López Montes wrote:
Hi,

Thank you for your reply,

I have already tried creating such statistics on t3.programme_identifier and t3.participant_identifier and the plan is the same, however I cannot create them for the right part of the join as they are from different tables (t1 and t2)
Of course, because for now, a join clause can't be estimated by extended statistics. It applies only to a scan filter (clause referencing only one relation). I have meant that with the development patch [1] applied, you may create two statistics on t3(participant_identifier,programme_identifier) and t2(participant_identifier,programme_identifier). These statistics would then be used to estimate the join clause and may resolve the problem.

[1] using extended statistics to improve join estimates
https://www.postgresql.org/message-id/flat/c8c0ff31-3a8a-7562-bbd3-78b2ec65f16c%40enterprisedb.com

--
regards, Andrei Lepikhov





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