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https://issues.apache.org/jira/browse/JCR-1253?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12553394
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Przemo Pakulski commented on JCR-1253:
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Thomas, I don't think so you can see noticeable difference using DerbyPM or any
other local database, you should try/test database accessible through local
network.
Jukka, I'm using SQL server and jtds driver, there are for sure additional
network calls.
Morover, in current implemntation there is also the potential risk that if
setting autocommit will throw exception then we could try to commit changeLog
twice.
And I still don't understand how autoCommt mode of private sql connection could
affect jackrabbit cluster, could anyone explain this ?
> Allow to configure autoCommit mode for BundleDB PM to avoid extra overhead
> when working in non clustered environment
> --------------------------------------------------------------------------------------------------------------------
>
> Key: JCR-1253
> URL: https://issues.apache.org/jira/browse/JCR-1253
> Project: Jackrabbit
> Issue Type: Improvement
> Components: jackrabbit-core
> Affects Versions: 1.4
> Reporter: Przemo Pakulski
> Priority: Minor
> Fix For: 1.4
>
> Attachments: single_checkin.JPG, small_change_log.JPG
>
>
> BundleDB PMs keeps connection open in autoCommit mode and during every store
> operation turn off/on this flag introducing some overhead.
> '... the reason is that in a clustered environment, the 'select' statements
> must be committed as well, otherwise the tables remain locked. and
> instead of explicitly commit each time after a read, we used the
> autocommit as default and switch it off during store ...'
> We could add additional parameter which allows to configure autoCommit mode,
> by default it could work as before, but specifing additional parameter will
> change the behaviour.
> It's hard to say about exact numbers how much overhead it is, there are to
> many variables (network speed/latency, db server type, jdbc driver, change
> log size). For sure it means 2 extra network calls, which could be easily
> avoided.
> See attached example screen from JProfiler using MSSQL server, and small
> change logs; overhead is about 20%. Doing simple checkin on versionable node
> it could be even 40%.
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