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RE: Cats, Pigeons and Open Cursors

From: Justin Cave <>
Date: Tue, 8 Jun 2004 03:56:41 -0600
Message-Id: <>

I think you are running into a fundamental problem. Once you return a cursor to the Java application, the Java application owns it. Oracle doesn't generally allow you to come along and kill things owned by another session.

The only ways I'm aware of to close the cursor would be to do so in the Java application or to kill the entire session from PL/SQL. If your Java developers are moderately competent, it should be relatively easy to walk through the code and ensure that all the cursors are closed by the appropriate exception block. If there are a few corner cases where cursors are not closed, you can cycle connections from the connection pool or close long-open connections from PL/SQL. The former option will probably cause your Java application fewer problems.

Justin Cave
Distributed Database Consulting, Inc.

-----Original Message-----

From: [] On Behalf Of Piet de Visser
Sent: Tuesday, June 08, 2004 3:31 AM
Subject: Cats, Pigeons and Open Cursors


We have a nice problem between Java and Pl/sql, and since PL/sql is slightly out of my comfort zone, I'm submitting it to the list (fairly sure we are not the first to stumble on this).

A procedure is used to open an number of ref-cursors and pass them back to java as out-parameters.
Which cursors are opened varies and depends on in-parameters.

When Java is done using the cursors,
it Should close all the opened cursors.

Sometimes the closing is skipped or forgotten, and the nr-open-cursors increases rapidly.
Since connections are rarely closed,
but rather re-used, the db runs out of open cursors.

Given the fact that we do not quite trust the Java code to always close all cursors, we would like to build a sure-fire way in Pl/sql to close all previously opened cursors.

First suggestion was to create another procedure that checks all cursors using ISOPEN%cursor123 and closes them.
This doesn't work because REF-cursors can apparently not be declared outside of functions or procedures.


   More precisely, we want the package to keep track of    all cursors it has opened (we can keep a list, no problem    if that requires some extra code). We then want the same    procedure or another procedure to go in, read the list    of open cursors, an close any that are still open.

Is this feasible ?
Suggestions anyone ?



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Received on Tue Jun 08 2004 - 04:55:45 CDT

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