Re: BTScanOpaqueData size slows down tests - Mailing list pgsql-hackers

From Tom Lane
Subject Re: BTScanOpaqueData size slows down tests
Date
Msg-id 883223.1743608193@sss.pgh.pa.us
Whole thread Raw
In response to BTScanOpaqueData size slows down tests  (Andres Freund <andres@anarazel.de>)
Responses Re: BTScanOpaqueData size slows down tests
Re: BTScanOpaqueData size slows down tests
List pgsql-hackers
Andres Freund <andres@anarazel.de> writes:
> Looking at the size of BTScanOpaqueData I am less surprised:
>         /* size: 27352, cachelines: 428, members: 17 */
> allocating, zeroing and freeing 28kB of memory for every syscache miss, yea,
> that's gonna hurt.

Ouch!  I had no idea it had gotten that big.  Yeah, we ought to
do something about that.

> And/or perhaps we could could allocate BTScanOpaqueData.markPos as a whole
> only when mark/restore are used?

That'd be an easy way of removing about half of the problem, but
14kB is still too much.  How badly do we need this items array?
Couldn't we just reference the on-page items?

            regards, tom lane



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