Re: Add table AM 'tid_visible'

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От Jinbao Chen
Тема Re: Add table AM 'tid_visible'
Дата
Msg-id 107F5954-F720-4D39-9071-2C8AB1B1CF7C@vmware.com
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Ответ на Re: Add table AM 'tid_visible'  (Andres Freund <andres@anarazel.de>)
Ответы Re: Add table AM 'tid_visible'
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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.





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