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 Mon, 14 Dec 2020 18:55:00 +0300 (MSK)
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From: Leonid Vasiliev <lvasiliev@tarantool.org>
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Date: Mon, 14 Dec 2020 18:54:00 +0300
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Subject: Re: [Tarantool-patches] [PATCH v2 3/3] sql: update temporary file
 name format
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To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>, imeevma@tarantool.org, korablev@tarantool.org, sergos@tarantool.org, m.semkin@corp.mail.ru
Cc: tarantool-patches@dev.tarantool.org

Hi! Thank you for the review.

On 13.12.2020 21:30, Vladislav Shpilevoy wrote:
> Thanks for the patch!
> 
> On 11.12.2020 15:49, Leonid Vasiliev via Tarantool-patches wrote:
>> The bug was consisted in fail when working with temporary files
>> created by VDBE to sort large result of a `SELECT` statement with
>> `ORDER BY`, `GROUP BY` clauses.
>>
>> Whats happen (step by step):
>> - We have two instances on one node (sharded cluster).
>> - A query is created that executes on both.
>> - The first instance creates the name of the temporary file and
>>    checks a file with such name on existence.
>> - The second instance creates the name of the temporary file
>>    (the same as in  first instance) and checks a file with such name
>>    on existence.
>> - The first instance creates a file with the `SQL_OPEN_DELETEONCLOSE`
>>    flag.
>> - The second instance opens(try to open) the same file.
>> - The first instance closes (and removes) the temporary file.
>> - The second instance tries to work with the file and fails.
>>
>> Why did it happen:
>> The temporary file name format has a random part, but the random
>> generator uses a fixed seed.
>>
>> When it was decided to use a fixed seed:
>> 32cb1ad298b2b55d8536a85bdfb3827c8c8739e1
> 
> To reference a commit we also usually include commit title in
> ("...") after the hash.

Changed to:

When it was decided to use a fixed seed:
32cb1ad298b2b55d8536a85bdfb3827c8c8739e1
("sql: drop useless code from os_unix.c")

> 
> The patch itself looks good.
>