Re: jsonb format is pessimal for toast compression

On Fri, Sep 12, 2014 at 1:11 PM, Josh Berkus <josh@agliodbs.com> wrote:
> On 09/12/2014 10:00 AM, Robert Haas wrote:
>> On Fri, Sep 12, 2014 at 1:00 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>>> On Thu, Sep 11, 2014 at 9:01 PM, Josh Berkus <josh@agliodbs.com> wrote:
>>>> So, I finally got time to test Tom's latest patch on this.
>>>>
>>>> TLDR: we want to go with Tom's latest patch and release beta3.
>>>>
>>>> Figures:
>>>>
>>>> So I tested HEAD against the latest lengths patch.  Per Arthur Silva, I
>>>> checked uncompressed times for JSONB against compressed times.  This
>>>> changed the picture considerably.
>>>
>>> Did you
>>
>> Blah.
>>
>> Did you test Heikki's patch from here?
>>
>> http://www.postgresql.org/message-id/53EC8194.4020804@vmware.com
>>
>> Tom didn't like it, but I thought it was rather clever.
>
> Yes, I posted the results for that a couple weeks ago; Tom had posted a
> cleaned-up version of that patch, but materially it made no difference
> in sizes or extraction times compared with Tom's lengths-only patch.
> Same for Arthur's tests.
>
> It's certainly possible that there is a test case for which Heikki's
> approach is superior, but if so we haven't seen it.  And since it's
> approach is also more complicated, sticking with the simpler
> lengths-only approach seems like the way to go.

Huh, OK.  I'm slightly surprised, but that's why we benchmark these things.

Thanks for following up on this.

-- 
Robert Haas
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