Re: jsonb format is pessimal for toast compression

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От Arthur Silva
Тема Re: jsonb format is pessimal for toast compression
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Msg-id CAO_YK0U3WStdsua_eqX+Gq3ZfD8-O33qheBjNz6C=u1T4y7yRA@mail.gmail.com
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Ответ на Re: jsonb format is pessimal for toast compression  (Arthur Silva <arthurprs@gmail.com>)
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On Wed, Aug 27, 2014 at 1:09 AM, Arthur Silva <arthurprs@gmail.com> wrote:
It won't be faster by any means, but it should definitely be incorporated if any format changes are made (like Tom already suggested).

I think it's important we gather at least 2 more things before making any calls:
* Josh tests w/ cache aware patch, which should confirm cache aware is indeed prefered
* Tests with toast hacked to use lz4 instead, which might ease any decisions


--
Arthur Silva



On Wed, Aug 27, 2014 at 12:53 AM, Peter Geoghegan <pg@heroku.com> wrote:
On Tue, Aug 26, 2014 at 8:41 PM, Arthur Silva <arthurprs@gmail.com> wrote:
> The difference is small but I's definitely faster, which makes sense since
> cache line misses are probably slightly reduced.
> As in the previous runs, I ran the query a dozen times and took the average
> after excluding runs with a high deviation.

I'm not surprised that it hasn't beaten HEAD. I haven't studied the
problem in detail, but I don't think that the "cache awareness" of the
new revision is necessarily a distinct advantage.

--
Peter Geoghegan


I'm attaching a quick-n-dirty patch that uses lz4 compression instead of pglz in case someone wants to experiment with it. Seems to work in my test env, I'll make more tests when I get home.

PS: gotta love gmail fixed defaults of top-posting...
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