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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrew Gierth <andrew@tao11.riddles.org.uk>
Cc: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@lists.postgresql.org, Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Alexander Kuzmenkov <a.kuzmenkov@postgrespro.ru>
Subject: Re: Performance improvements for src/port/snprintf.c
Date: Fri, 05 Oct 2018 23:16:13 -0400
Message-ID: <13967.1538795773@sss.pgh.pa.us> (raw)
In-Reply-To: <87sh1jaiyq.fsf@news-spur.riddles.org.uk>
References: <28321.1538585692@sss.pgh.pa.us>
	<20181003170043.thdyezozi343dkuc@alap3.anarazel.de>
	<2132.1538587869@sss.pgh.pa.us>
	<20181003173639.tncawup2nnkp7vbv@alap3.anarazel.de>
	<2435.1538588403@sss.pgh.pa.us>
	<20181003174513.wxjxfj7eepytnlqa@alap3.anarazel.de>
	<3316.1538589695@sss.pgh.pa.us>
	<20181003183552.xaams6fau3i7oybj@alap3.anarazel.de>
	<6797.1538592539@sss.pgh.pa.us>
	<30726.1538754899@sss.pgh.pa.us>
	<20181005165819.h7gdzcbwhnhofq2b@alap3.anarazel.de>
	<87sh1jaiyq.fsf@news-spur.riddles.org.uk>

Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
> So here's a thing: I finally got to doing my performance tests for using
> the Ryu float output code in float[48]out.
> Ryu is so blazing fast that with it, COPY of a table with 2million rows
> of 12 random float8 columns (plus id) becomes FASTER in text mode than
> in binary mode (rather than ~5x slower):

Oh yeah?  Where's the code for this?

> (And yes, I've double-checked the results and they look correct, other
> than the formatting differences. COPY BINARY seems to have a bit more
> overhead than text mode, even for just doing integers, I don't know
> why.)

The per-column overhead is more (length word vs delimiter) and I think
the APIs for send/recv functions are potentially a bit less efficient
too.

			regards, tom lane




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