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Re: ODBC connection - extra statements being run

From: Norman Dunbar <>
Date: Thu, 09 Feb 2006 15:53:37 +0000
Message-Id: <>

Hi Ethan,

Norman Dunbar.
Contract Oracle DBA.
Rivers House, Leeds.

Internal : 7 28 2051
External : 0113 231 2051

>>> Ethan Post <> 02/09/06 03:19pm >>>
>> Nothing wrong with ODBC when used right.

But, how do you guarantee that 'using it properly' is what will happen ?
The user builds a query in Access using the Wizard. This generates a statement which seems to allow a LIKE on a LONG - which Oracle expressely forbids. No error is generated - unlike SQLPLus or TOAD whihc barfs at the parse stage.
The (now broken) query is submitted with the WHERE clause is quietly dropped - we now have a potential problem, depending on the number of tables in the query - a huge cartesian join results.

Access is quite happy to pull all of a LONG back from Oracle, do some internal conversion (I assume) and the apply the WHERE clause locally, unfortunately, the remote Oracle database is being hit more than it needs to be.

Obviously, if I don't have LONGs in the database, I don't get this problem and maybe the 'using it right' bit then applies. Unfortunately, the version of Avvess we have doesn't let you create queries against CLOBs.

>> How did a query using this level of resources go unnoticed for over
a week?

It didn't appear on any monitoring system until (I assume) it hit the sort. Up until then everything was fine. No user complaints or anything.


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Received on Thu Feb 09 2006 - 09:53:37 CST

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