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From Oleg Nitz ...@ukr.net>
Subject Re: default isolation level
Date Sun, 22 Dec 2002 17:53:45 GMT
Hi Raghu,

I agree with you. Maybe we need some special value of "isolation-level" 
attribute in repository.xml, something like "default" or "none"?


On Sunday 22 December 2002 15:27, you wrote:
> Please be careful about managed environments. You should not call
> setTransactionIsolation from within a JTA transaction. I would much rather
> allow an API to modify the isolation level and allow the user to set the
> isolation level, if he so chooses to. Otherwise, we should leave it at the
> isolation level set either through the driver's defaultIsolationLevel or
> through ejb's isolation specification. I would prefer OJB not to set any
> isolation level explicitly.
> My two cents...
> Raghu.
> -----Original Message-----
> From: Oleg Nitz
> To: OJB Developers List
> Sent: 12/22/2002 12:03 PM
> Subject: default isolation level
> Hi All,
> I've noticed that OJB seems to use READ_UNCOMMITTED isolation level by
> default. But
> 1) AFAIK with READ_COMMITTED isolation level database server works much
> faster, at least this is true for Sybase ASE. I suppose that for
> READ_UNCOMMITTED level table indices can't be used at all because they
> are
> updated on commit, so any query on uncommitted data requires full table
> scans, for queries with joins on big tables the difference of execution
> time
> with READ_COMMITTED and with READ_UNCOMMITTED is amazing.
> 2) I haven't found any setTransactionIsolation() calls in OJB code, so I
> suppose that isolation-level attribute in repository.xml is simply
> ignored
> now, OJB works always in READ_COMMITTED mode, which is good for
> performance
> :-)
> So I propose to fix 2) and to set level to READ_COMMITTED by default.
> I could do this.
> Regards,
>  Oleg

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