Re: GIN data corruption bug(s) in 9.6devel

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: GIN data corruption bug(s) in 9.6devel
Date: 2015-12-23 20:33:42
Message-ID: CAMkU=1w-zo8genqMa8Y0+fGWBNJrkZH_Uri6-BdRicmb8CB_yw@mail.gmail.com
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On Mon, Dec 21, 2015 at 11:51 AM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>
>
> On 12/21/2015 07:41 PM, Jeff Janes wrote:
>>
>> On Sat, Dec 19, 2015 at 3:19 PM, Tomas Vondra
>> <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>
>
> ...
>
>>> So both patches seem to do the trick, but (2) is faster. Not sure
>>> if this is expected. (BTW all the results are without asserts
>>> enabled).
>>
>>
>> Do you know what the size of the pending list was at the end of each
>> test?
>>
>> I think last one may be faster because it left a large mess behind
>> that someone needs to clean up later.
>
>
> No. How do I measure it?

pageinspect's gin_metapage_info, or pgstattuple's pgstatginindex

>
>>
>> Also, do you have the final size of the indexes in each case?
>
>
> No, I haven't realized the patches do affect that, so I haven't measured it.

There shouldn't be a difference between the two approaches (although I
guess there could be if one left a larger pending list than the other,
as pending lists is very space inefficient), but since you included
9.5 in your test I thought it would be interesting to see how either
patched version under 9.6 compared to 9.5.

Cheers,

Jeff

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