Horton

Re: WIP: Faster Expression Processing v4

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, pgsql-hackers@postgresql.org
Date: 2017-03-22T15:00:38Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> On 2017-03-22 10:41:06 -0400, Tom Lane wrote:
>> * execQual.c doesn't seem to have a unifying reason to exist anymore.
>> It certainly has little to do with evaluating typical qual expressions;
>> what's left in there seems to be mostly concerned with SRFs.  I feel
>> like it might be a good idea to rename it, but to what?  execExprUtils.c
>> perhaps?  Or maybe we should destroy it altogether, shoving the SRF
>> stuff into nodeFunctionscan.c and moving what little remains into
>> execUtils.c.

> Yea, I was wondering about that too.  What would we do with
> GetAttributeByName/Num?

I was thinking execUtils.c for those.

>> * I do not like the function name ExecInstantiateExpr().  Webster's
>> defines "instantiate" as "to represent (an abstraction) by a concrete
>> instance", which does not seem to me to have a lot to do with what this
>> function actually does.
>> ...

> Either of those work, but they don't strike me as perfect either, but I
> can't come up with something better (ExecReadyExprForExec()?).

Actually, ExecReadyExpr seems kind of nice for this (using "ready" in its
verb sense, "to prepare (someone or something) for an activity or
purpose").

			regards, tom lane

Commits

  1. Improve performance of ExecEvalWholeRowVar.

  2. Remove unreachable code in expression evaluation.

  3. Faster expression evaluation and targetlist projection.

  4. Avoid syntax error on platforms that have neither LOCALE_T nor ICU.

  5. Add configure test to see if the C compiler has gcc-style computed gotos.

  6. Improve regression test coverage for TID scanning.

  7. Improve expression evaluation test coverage.

  8. Fix two errors with nested CASE/WHEN constructs.