Horton

Re: Pre-alloc ListCell's optimization

Stephen Frost <sfrost@snowman.net>

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From: Stephen Frost <sfrost@snowman.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Alvaro Herrera <alvherre@commandprompt.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2012-05-16T17:03:57Z
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 →

  1. Replace the parser's namespace tree (which formerly had the same

  2. Turns out that my recent elimination of the 'redundant' flatten_andors()

* Stephen Frost (sfrost@snowman.net) wrote:
> So, when it comes to palloc() reduction, this patch would eliminate 99%
> of palloc's due to lists.  For the regression tests, we're talking about
> reducing 893,206 palloc calls to only 1.

Apologies, that wasn't quite right- it'd reduce it to 1 palloc call for
each of the 893,206 lists.  In terms of actual comparison of palloc
calls, we have to look at how many are done today for those lists:

palloc calls for:

1-node lists: 1143794
2-node lists: 673071
3-node lists: 205364
4-node lists: 133650
5-node lists: 60552
6-node lists: 28896
7-node lists: 13248
8-node lists: 27045

Total: 2,285,620

Instead, we'd have 1 palloc call for each list, or 893,206, so we'd be
removing ~1.4M calls across the regression suite.

I'll work on cleaning up the patch to be committable early in the 9.3
dev cycle, so it can get a lot of testing prior to the next release.

	Thanks,
	
		Stephen