Re: Inlining comparators as a performance optimisation

Greg Stark <stark@mit.edu>

From: Greg Stark <stark@mit.edu>

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

Cc: Andrew Dunstan <andrew@dunslane.net>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, Peter Geoghegan <peter@2ndquadrant.com>, PG Hackers <pgsql-hackers@postgresql.org>

Date: 2011-09-21T16:04:21Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Speed up conversion of signed integers to C strings.
- 4fc115b2e981 9.1.0 cited
Remove some unnecessary tests of pgstat_track_counts.
- f4d242ef9473 9.1.0 cited
Remove cvs keywords from all files.
- 9f2e21138693 9.1.0 cited
Code cleanup for function prototypes: change two K&R-style prototypes
- b9954fbb4ef2 8.3.0 cited
Use Min() instead of min() in qsort, for consistency and to avoid
- b38900c76776 8.2.0 cited
pgindent run for 8.2.
- f99a569a2ee3 8.2.0 cited
Switch over to using our own qsort() all the time, as has been proposed
- 6edd2b4a91bd 8.2.0 cited

On Wed, Sep 21, 2011 at 4:46 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>  As such, they could not have entries in pg_proc, so
> it seems like there's no ready way to represent them in the catalogs.

Why couldn't they be in pg_proc with a bunch of opaque arguments like
the GIST opclass support functions?

I'm a bit puzzled what the arguments would look like. They would still
need to know the collation, nulls first/last flags, etc.
And calling it would still not be inlinable.  So they would have to
check those flags on each invocation instead of having a piece of
straightline code that hard codes the behaviour with the right
behaviour inline.  ISTM the hope for a speedup from the inlining
mostly came from the idea that the compiler might be able to hoist
this logic outside the loop (and I suppose implement n specialized
loops depending on the behaviour needed).

-- 
greg