Sv: Re: data-checksums
På tirsdag 09. januar 2018 kl. 21:37:16, skrev Joshua D. Drake <jd@commandprompt.com>:
On 01/09/2018 12:22 PM, Andres Freund wrote:
> On 2018-01-09 20:04:04 +0100, Rakesh Kumar wrote:
>>>> I also would like to believe that the hit is small, but when PG
>>>> official document writes "noticeable performance penalty", it becomes
>>>> difficult to convince management that the hit is small :-)
>>> Why believe, when you can measure?
>> yup doing that. But I still feel that PG documentation should stay
>> away from such scare mongering. Or did the lawyers write that :)
> So we should rather lie about it having a potential for performance
> impact? Who'd be helped by that?
It isn't a lie, it depends on the workload and hardware. Adjusting the
documentation to say something like the following probably isn't a bad idea:
The use of the data checksum feature may incur a performance penalty.
However, this does depend on your particular workload and provisioned
hardware. It is wise to test the feature based on your specific
requirements.
Does PG use HW-accellerated crc if CPU supports it[1]?
[1] https://en.wikipedia.org/wiki/SSE4
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Andreas Joseph Krogh
CTO / Partner - Visena AS
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