Horton

Re: SendRowDescriptionMessage() is slow for queries with a lot of columns

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org
Date: 2017-09-28T04:06:49Z
Lists: pgsql-hackers 
On 2017-09-28 00:01:53 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > Attached is an extension of the already existing pg_bswap.h that
> > a) adds 16 bit support
> > b) moves everything to inline functions, removing multiple evaluation
> >    hazards that were present everywhere.
> > c) adds pg_nto{s,l,ll} and pg_hton{s,l,ll} wrappers that only do work
> >    if necessary.
> 
> Could we please not perpetuate the brain-dead "s" and "l" suffixes
> on these names?  Given the lack of standardization as to how long
> "long" is, that's entirely unhelpful.  I'd be fine with names like
> pg_ntoh16/32/64 and pg_hton16/32/64.

Yes. I'd polled a few people and they leaned towards those. But I'm
perfectly happy to do that renaming.

Greetings,

Andres Freund

Commits

  1. Replace remaining uses of pq_sendint with pq_sendint{8,16,32}.

  2. Improve performance of SendRowDescriptionMessage.

  3. Use one stringbuffer for all rows printed in printtup.c.

  4. Add configure infrastructure to detect support for C99's restrict.

  5. Add more efficient functions to pqformat API.

  6. Allow to avoid NUL-byte management for stringinfos and use in format.c.

  7. Replace most usages of ntoh[ls] and hton[sl] with pg_bswap.h.

  8. Extend & revamp pg_bswap.h infrastructure.