Re: Dirty Read Issue

[Thomas Mahler]

Hi Bill,

Bill Brooks wrote:

Hi,

I am working on a project that is using OJB checked out from CVS at
jakarta.apache.org and have been having a good amount of success (thanks to
the OJB developers for their work).  But I am running into an issue with
'dirty-reads'.

My understanding is that if in the repository.xml file I have
isolation-level="read-uncommitted" set then I can do the following:

1) start a transaction (using ODMG)
2) create a new object
3) lock the object (with lock mode of WRITE)
4) work with other objects
5) use a finder to select the newly created object (created in step #2)
using non-primary key fields

OJB queries work against the DB only. Thus the uncommited Object won't be found by a query.
But it is in the cache and could be found by primary key lookup!

6) update the object (found in step #5)
7) commit the transaction

The issue that I have is that in step #5 when I try to find the newly
created object, I do not find it.  I have checked the mail archives but have
not run across something that would help me.

This is a limitation of our implementation. All queries are executed as SQL queries against the database.
To have queries retrieve uncommited objects we would have to implement a query interpreter that also search the transactions ObjectEnvelopeTable.
It's possible to write such a beast, sure, but it would be a major task to do!

As always: any volunteers?

cheers,
Thomas

Is anyone else having this issue?  Is there some configuration that I have
missed?

Any input would be appreciated.

Bill



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