Re: Fix gin index cost estimation - Mailing list pgsql-hackers

From Ronan Dunklau
Subject Re: Fix gin index cost estimation
Date
Msg-id 10184681.nUPlyArG6x@aivenlaptop
Whole thread Raw
In response to Re: Fix gin index cost estimation  (Alexander Korotkov <aekorotkov@gmail.com>)
Responses Re: Fix gin index cost estimation  (Ronan Dunklau <ronan.dunklau@aiven.io>)
List pgsql-hackers
Le vendredi 2 décembre 2022, 12:33:33 CET Alexander Korotkov a écrit :
> Hi, Ronan!
> Thank you for your patch.  Couple of quick questions.
> 1) What magic number 50.0 stands for?  I think we at least should make
> it a macro.

This is what is used in other tree-descending  estimation functions, so I used
that too. Maybe a DEFAULT_PAGE_CPU_COST macro would work for both ? If so I'll
separate this into two patches, one introducing the macro for the other
estimation functions, and this patch for gin.

> 2) "We only charge one data page for the startup cost" – should this
> be dependent on number of search entries?

Good point, multiplying it by the number of search entries would do the trick.

Thank you for looking at this !

Regards,

--
Ronan Dunklau






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