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Re: NFS performance regression in 1.9

From: Philip Martin <philip.martin_at_wandisco.com>
Date: Fri, 16 Oct 2015 12:14:36 +0100

Philip Martin <philip.martin_at_wandisco.com> writes:

> "Bert Huijben" <bert_at_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
Received on 2015-10-16 13:15:01 CEST

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