Re: Add table AM 'tid_visible' - Mailing list pgsql-hackers

From Jinbao Chen
Subject Re: Add table AM 'tid_visible'
Date
Msg-id 107F5954-F720-4D39-9071-2C8AB1B1CF7C@vmware.com
Whole thread Raw
In response to Re: Add table AM 'tid_visible'  (Andres Freund <andres@anarazel.de>)
Responses Re: Add table AM 'tid_visible'  (Masahiko Sawada <sawada.mshk@gmail.com>)
List pgsql-hackers
Hi Andres,



> Yea, it's something we should improve. Have you checked if this has

> performance impact for heap? Should we also consider planning costs?

Since the visibility map is very small, all pages of the visibility map will

usually reside in memory. The IO cost of accessing the visibility map can

be ignored. We should add the CPU cost of accessing visibility map. The

CPU cost of accessing visibility map is usually smaller than cpu_tuple_cost.

But Postgres does not have a Macro to describe such a small cost. Should

We add one?



> As far as I can tell you have not acually attached the patch.

Ah, forgot to upload the patch. Attach it below.





Attachment

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