Re: Cutting initdb's runtime (Perl question embedded)

From: ilmari(at)ilmari(dot)org (Dagfinn Ilmari =?utf-8?Q?Manns=C3=A5ker?=)
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andreas Karlsson <andreas(at)proxel(dot)se>, pgsql-hackers(at)postgreSQL(dot)org, Andres Freund <andres(at)anarazel(dot)de>
Subject: Re: Cutting initdb's runtime (Perl question embedded)
Date: 2017-04-17 16:49:54
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Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> There's certainly lots more that could be done in the genbki code,
> but I think all we can justify at this stage of the development
> cycle is to get the low-hanging fruit for testing speedups.

I threw Devel::NYTProf at it and picked some more low-hanging fruit.
Attached are separate patches for each change, and here are the runtimes
of and, respectively, after each patch
(averages of 5 runs, in millseconds):

master (b6dd1271): 355, 182

1: Avoid unnecessary regex captures: 349, 183
2: Avoid repeated calls to SplitDataLine: 316, 158
3: Inline SplitDataLine: 291, 141
4: Inline check_natts: 287, 141

Together they shave 68ms or 19.2% off the runtime of and 41ms
or 22.5% off the runtime of

Finally, one non-performance patch, which just removes the use of
Exporter in, since none of the users actually import anything
from it.

- ilmari
"I use RMS as a guide in the same way that a boat captain would use
a lighthouse. It's good to know where it is, but you generally
don't want to find yourself in the same spot." - Tollef Fog Heen

Attachment Content-Type Size text/x-diff 1.2 KB
0002-Avoid-repeated-calls-to-Catalog-SplitDataLine.patch text/x-diff 3.2 KB
0003-Inline-SplitDataLines-into-its-only-caller.patch text/x-diff 2.8 KB
0004-Inline-check_nattrs-into-its-only-caller.patch text/x-diff 1.8 KB text/x-diff 988 bytes

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