Horton

Re: WIP: Faster Expression Processing v4

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

View thread View on postgr.es
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: 2017-03-20T15:16:12Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> On 2017-03-15 20:09:03 -0400, Tom Lane wrote:
>> I think it would be worth creating a README file giving an overview
>> of how all of this patch is supposed to work.  You also need to do a
>> whole lot more work on the function-level comments.

> I tried to improve upon both fronts.  I've added the higher level
> explanation to executor/README, but I don't feel very strong about that.

> I'm not quite sure it's exactly what you wanted however, the above ask
> could also be understood to have more of an motivational angle,
> describing why and what exactly is changed?  I'm also still not sure how
> understandable it's for anybody that hasn't had their head in this for a
> while...

Well, I wasn't totally sure what was needed either.  I'm coming to this
relatively fresh, having paid little attention to the thread up to now,
so maybe I'll try to add material to what you wrote as I figure things
out.

> Did I understand correctly that you'd rather just merge
> ExecGetLastAttnums into execExpr.c, instead of making it globally
> available?

Yeah, just moving it over seems like the thing to do for now.  We can
expose it later if there proves to be an actual reason to do that,
but as I mentioned, I'm doubtful that there will be one.

I'll start reading these...

			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.