Horton

Re: WIP: Faster Expression Processing and Tuple Deforming (including JIT)

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@postgresql.org, Heikki Linnakangas <hlinnaka@iki.fi>, Doug Doole <ddoole@salesforce.com>
Date: 2016-12-15T17:50:00Z
Lists: pgsql-hackers 
On Tue, Dec  6, 2016 at 11:10:59AM -0800, Andres Freund wrote:
> > I concur with your feeling that hand-rolled JIT is right out.  But
> > I'm not sure that whatever performance gain we might get in this
> > direction is worth the costs.
> 
> Well, I'm not impartial, but I don't think we do our users a service by
> leaving significant speedups untackled, and after spending a *LOT* of
> time on this, I don't see much other choice than JITing. Note that
> nearly everything performance sensitive is moving towards doing JITing
> in some form or another.

Agreed, we don't really have a choice.  After all the optimizations we
have done to so many subsystems, our executor is relatively slow and is
a major drag on our system, specifically for long-running queries.  The
base problem with the executor are the state machines at so many levels,
and we really can't optimize that while keeping a reasonable maintenance
burden.

This is where JIT and LLVM help.  I outlined two external projects that
were researching this in this blog entry:

	http://momjian.us/main/blogs/pgblog/2016.html#April_1_2016

I am excited to now be seeing WIP code.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

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.