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From: Philip Martin <philip.martin@wandisco.com>
To: "Bert Huijben" <bert@qqmail.nl>
Cc: 'Branko =?utf-8?Q?=C4=8Cibej'?= <brane@apache.org>,
  <dev@subversion.apache.org>
Subject: Re: NFS performance regression in 1.9
References: <87vba82pgl.fsf@wandisco.com> <561FD7F4.3090604@apache.org>
	<87k2qo2fpy.fsf@wandisco.com>
	<0f7101d10776$412ba610$c382f230$@qqmail.nl>
	<87fv1c2cqy.fsf@wandisco.com>
Date: Fri, 16 Oct 2015 12:14:36 +0100
In-Reply-To: <87fv1c2cqy.fsf@wandisco.com> (Philip Martin's message of "Thu,
	15 Oct 2015 19:44:05 +0100")
Message-ID: <871tcvgj4z.fsf@wandisco.com>
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Philip Martin <philip.martin@wandisco.com> writes:

> "Bert Huijben" <bert@qqmail.nl> writes:
>
>> I'm not able to answer all that, but I do know that your change will
>> slow Subversion down on Samba shares as used from Windows systems with
>> that flag. And once one user used it in that way it will stay slow
>> because the journal mode is stored in the database.
>>
>> I don't think just touching a working copy with a client should ever
>> have such an effect on a working copy.
>
> The journal mode is set to TRUNCATE every time we open the database,
> that doesn't change with my patch.  Are you saying that TRUNCATE will be
> ignored after some previous connection uses DELETE?

The documentation explicitly states that journal_mode=WAL stays in
effect for later connections, but doesn't say the same for the other
modes:

https://sqlite.org/pragma.html#pragma_journal_mode

and that is what I see. journal_mode=delete applies unless we set
truncate and the truncate is temporary:

$ svnadmin create repo
$ svn co file://`pwd`/repo wc
$ sqlite3 wc/.svn/wc.db "pragma journal_mode"
delete
$ sqlite3 wc/.svn/wc.db "pragma journal_mode=truncate"
truncate
$ sqlite3 wc/.svn/wc.db "pragma journal_mode"
delete
$ svn st wc
$ sqlite3 wc/.svn/wc.db "pragma journal_mode"
delete
$ svn st wc --config-option config:working-copy:exclusive-locking=true
$ sqlite3 wc/.svn/wc.db "pragma journal_mode"
delete


-- 
Philip Martin
WANdisco