Re: [HACKERS] WIP: Faster Expression Processing v4 - Mailing list pgsql-hackers

From Douglas Doole
Subject Re: [HACKERS] WIP: Faster Expression Processing v4
Date
Msg-id CADE5jY+=ZDBMcyNzL_HRxy72OdENGerhYt_VyooE1cM05tZBRg@mail.gmail.com
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In response to Re: [HACKERS] WIP: Faster Expression Processing v4  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
On Tue, Mar 14, 2017 at 3:16 PM Andres Freund <andres@anarazel.de> wrote:
Hm.  Right now ExprState's are allocated in several places - but we
could easily move that to a central place.  Have a bit of a hard time
seing that that branch during *initialization* time is that expensive,
especially given that previously we allocated a lot of memory separately
too.

I didn't make any comparisons of the cost of the new init against the old init with this change in particular - I just saw that it made the new init faster. I also didn't play around to determine if the savings was found in removing the branch misprediction or inlining or both.

I certainly wouldn't hold up your commit for this, but it's something that might be worth a second look once the dust has settled.

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