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From "Armin Waibel" <ar...@code-au-lait.de>
Subject Re: default isolation level
Date Sun, 22 Dec 2002 16:04:34 GMT
Hi all,

I think that declared isolation-level is used for locking strategy
on ODMG level and doesn't bother the db connection stuff.

regards,
Armin

----- Original Message -----
From: "Oleg Nitz" <on@ukr.net>
To: "OJB Developers List" <ojb-dev@jakarta.apache.org>
Sent: Sunday, December 22, 2002 6:03 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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