From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <sergos@tarantool.org>
Received: from smtp48.i.mail.ru (smtp48.i.mail.ru [94.100.177.108])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by dev.tarantool.org (Postfix) with ESMTPS id 5CD8B45C305
 for <tarantool-patches@dev.tarantool.org>;
 Wed, 16 Dec 2020 00:07:24 +0300 (MSK)
Content-Type: text/plain;
	charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.4\))
From: Sergey Ostanevich <sergos@tarantool.org>
In-Reply-To: <6968e1d8-5bab-d043-ebeb-fc2bbbdea069@tarantool.org>
Date: Wed, 16 Dec 2020 00:07:22 +0300
Content-Transfer-Encoding: 7bit
Message-Id: <37DB5DC7-2188-4ECF-8337-19350F9E0D57@tarantool.org>
References: <cover.1607696813.git.lvasiliev@tarantool.org>
 <59ffd9dd6c9e895b85f89bfb23d6f8fcbf2c556f.1607696813.git.lvasiliev@tarantool.org>
 <8e8dff1a-13fe-b64a-14e3-892f69def428@tarantool.org>
 <6968e1d8-5bab-d043-ebeb-fc2bbbdea069@tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH v2 3/3] sql: update temporary file
 name format
List-Id: Tarantool development patches <tarantool-patches.dev.tarantool.org>
List-Unsubscribe: <https://lists.tarantool.org/mailman/options/tarantool-patches>, 
 <mailto:tarantool-patches-request@dev.tarantool.org?subject=unsubscribe>
List-Archive: <https://lists.tarantool.org/pipermail/tarantool-patches/>
List-Post: <mailto:tarantool-patches@dev.tarantool.org>
List-Help: <mailto:tarantool-patches-request@dev.tarantool.org?subject=help>
List-Subscribe: <https://lists.tarantool.org/mailman/listinfo/tarantool-patches>, 
 <mailto:tarantool-patches-request@dev.tarantool.org?subject=subscribe>
To: Leonid Vasiliev <lvasiliev@tarantool.org>
Cc: m.semkin@corp.mail.ru, Vladislav Shpilevoy <v.shpilevoy@tarantool.org>, tarantool-patches@dev.tarantool.org

Thanks for the patch!

As I mentioned in another thread - this one is LGTM.

Sergos

> On 14 Dec 2020, at 18:54, Leonid Vasiliev <lvasiliev@tarantool.org> wrote:
> 
> 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.