Horton

Re: Allowing printf("%m") only where it actually works

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>, Thomas Munro <thomas.munro@enterprisedb.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-09-26T22:45:47Z
Lists: pgsql-hackers 
On 2018-09-26 18:31:07 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2018-09-26 17:41:36 -0400, Tom Lane wrote:
> >> Well, if you're unhappy about snprintf.c's performance, you could review
> >> https://commitfest.postgresql.org/19/1763/
> >> so I can push that.  In my tests, that got us down to circa 10% penalty
> >> for float conversions.
> 
> > Uh, I can do that, but the fact remains that your commit slowed down
> > COPY and other conversion intensive workloads by a *significant* amount.
> 
> [ shrug... ]  There are other cases that got faster (particularly after
> the above-mentioned patch).  I do not wish to consider floating-point
> conversion speed as the sole figure of merit for this change.  If we
> are to consider only the worst-case, we should be reverting JIT.

Oh, come on. One can be disabled with a GUC, has (although not good
enough) intelligence when it switches on, the other has ... none of
that.  Obviously performance is always a balancing act, but you'd be
pretty pissed at anybody else regressing performance in a non-fringe
case, and then refused responsibility.  And as I said, I'm willing to
help.

Greetings,

Andres Freund

Commits

  1. In pg_log_generic(), be more paranoid about preserving errno.

  2. Make src/common/exec.c's error logging less ugly.

  3. Select appropriate PG_PRINTF_ATTRIBUTE for recent NetBSD.

  4. Fix detection of the result type of strerror_r().

  5. Try another way to detect the result type of strerror_r().

  6. Clean up *printf macros to avoid conflict with format archetypes.

  7. Fix link failures due to snprintf/strerror changes.

  8. Implement %m in src/port/snprintf.c, and teach elog.c to rely on that.

  9. Always use our own versions of *printf().

  10. Incorporate strerror_r() into src/port/snprintf.c, too.

  11. Convert elog.c's useful_strerror() into a globally-used strerror wrapper.

  12. Revert "Distinguish printf-like functions that support %m from those that don't."

  13. Produce compiler errors if errno is referenced inside elog/ereport calls.

  14. Distinguish printf-like functions that support %m from those that don't.

  15. Fix unportable usage of printf("%m").

  16. Be more robust when strerror() doesn't give a useful result.