Re: Performance improvements for src/port/snprintf.c

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От Andres Freund
Тема Re: Performance improvements for src/port/snprintf.c
Дата
Msg-id 20180927011814.kpncoksuqq3gy44s@alap3.anarazel.de
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Ответ на Re: Performance improvements for src/port/snprintf.c  (Andres Freund <andres@anarazel.de>)
Ответы Re: Performance improvements for src/port/snprintf.c  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Performance improvements for src/port/snprintf.c  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Performance improvements for src/port/snprintf.c  (Thomas Munro <thomas.munro@enterprisedb.com>)
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Hi,

On 2018-09-26 17:57:05 -0700, Andres Freund wrote:
> snprintf time = 1324.87 ms total, 0.000264975 ms per iteration
> pg time = 1434.57 ms total, 0.000286915 ms per iteration
> stbsp time = 552.14 ms total, 0.000110428 ms per iteration

Reading around the interwebz lead me to look at ryu

https://dl.acm.org/citation.cfm?id=3192369
https://github.com/ulfjack/ryu/tree/46f4c5572121a6f1428749fe3e24132c3626c946

That's an algorithm that always generates the minimally sized
roundtrip-safe string output for a floating point number. That makes it
insuitable for the innards of printf, but it very well could be
interesting for e.g. float8out, especially when we currently specify a
"too high" precision to guarantee round-trip safeity.

Greetings,

Andres Freund


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