Horton

Re: Query is over 2x slower with jit=on

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Andreas Joseph Krogh <andreas@visena.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-04-18T19:16:35Z
Lists: pgsql-hackers 
On Wed, Apr 18, 2018 at 11:50 AM, Andres Freund <andres@anarazel.de> wrote:
> JIT has cost, and sometimes it's not beneficial. Here our heuristics
> when to JIT appear to be a bit off. In the parallel world it's worse
> because the JITing is duplicated for parallel workers atm.

It seems like you're describing it as if the JIT just didn't produce
gains sufficient to make up for the cost of doing it, but that's not
really the issue here AFAICS.  Here the JIT actually made code that
run slower than the un-JIT-ted code.  That seems like a different sort
of problem.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Fix issues around EXPLAIN with JIT.

  2. Collect JIT instrumentation from workers.

  3. Make EXPLAIN output for JIT compilation more dense.

  4. Save/restore SPI's global variables in SPI_connect() and SPI_finish().

  5. Rationalize handling of single and double quotes in bootstrap data.