Re: [BUG] false positive in bt_index_check in case of short 4B varlena datum

From: Michael Zhilin <m(dot)zhilin(at)postgrespro(dot)ru>
To: "Andrey M(dot) Borodin" <x4mmm(at)yandex-team(dot)ru>, Alexander Lakhin <exclusion(at)gmail(dot)com>, jian(dot)universality(at)gmail(dot)com
Cc: pgsql-bugs(at)postgresql(dot)org, Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru>
Subject: Re: [BUG] false positive in bt_index_check in case of short 4B varlena datum
Date: 2024-01-23 19:24:11
Message-ID: 68d87456-634d-44dc-b2ae-077f3601f71e@postgrespro.ru
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Hi,

Thank you, Jian, for nice comments!
PFA version with your recommendations.

Andrey,
I didn't yet check your patches, but at least compiler complains about
added, but unused variable "miss_oversized_tuple".

verify_nbtree.c:2898:7: warning: unused variable 'miss_oversized_tuple'
[-Wunused-variable]
        bool miss_oversized_tuple = false;

So patch has been updated to fix this warning.

Attached v4, rebased version with Jian's comments & removed unused variable.

Thanks,
 Michael.

On 1/23/24 21:09, Andrey M. Borodin wrote:
>
>> On 20 Jan 2024, at 09:00, Alexander Lakhin<exclusion(at)gmail(dot)com> wrote:
>>
>>> Alexander, do you plan to provide fixes for bugs you discovered?
>> No, I don't have a concrete proposal how to fix those bugs. I'd thought
>> that fixing the whole class of such anomalies, not only one case, is a good
>> thing to do, but if it's too complicated, maybe other similar bugs could be
>> put aside.
> PFA draft fixes for both this errors. Alexander, Michael, Jian, what do you think?
>
> I did not touch anything in first step - fix for original bug in this thread. However, I think that comments from Jian He worth incorporating into the fix.
>
>
> Best regards, Andrey Borodin.
>

--
Michael Zhilin
Postgres Professional
+7(925)3366270
https://www.postgrespro.ru

Attachment Content-Type Size
v4-0001-contrib-amcheck-must-support-different-header-siz.patch text/x-patch 6.1 KB
v4-0002-amcheck-prevent-false-positives-from-extended-dat.patch text/x-patch 2.9 KB
v4-0003-amcheck-avoid-failing-on-oversized-tuples.patch text/x-patch 6.0 KB

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