Re: Slow 3 Table Join with v bad row estimate - Mailing list pgsql-performance

From Igor Neyman
Subject Re: Slow 3 Table Join with v bad row estimate
Date
Msg-id A76B25F2823E954C9E45E32FA49D70ECCD583368@mail.corp.perceptron.com
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In response to Re: Slow 3 Table Join with v bad row estimate  (David Osborne <david@qcode.co.uk>)
Responses Re: Slow 3 Table Join with v bad row estimate  (David Osborne <david@qcode.co.uk>)
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From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of David Osborne
Sent: Tuesday, November 10, 2015 12:32 PM
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Slow 3 Table Join with v bad row estimate

 

Ok - wow.

 

Adding that index, I get the same estimate of 1 row, but a runtime of ~450ms.
A 23000ms improvement.

 

 

This is great. So as a general rule of thumb, if I see a Join Filter removing an excessive number of rows, I can check if that condition can be added to an index from the same table which is already being scanned.

 

Thanks for this!

 

David,

I believe the plan you are posting is the old plan.

Could you please post explain analyze with the index that Tom suggested?

 

Regards,

Igor Neyman

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