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From "Andreas Korneliussen (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1696) transaction may sometimes keep lock on a row after moving off the resultset in scrollable updatable resultset
Date Sat, 16 Sep 2006 10:41:23 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1696?page=comments#action_12435207 ] 
Andreas Korneliussen commented on DERBY-1696:

I will update the patch for this issue once the DERBY-1799 is reviewed and committed, since
these patches do have a minor conflict. Basically, the same approach will be used for this
patch (using reopenScan()) to release locks when moving to afterlast /beforefirst).

> transaction may sometimes keep lock on a row after moving off the resultset in scrollable
updatable resultset
> -------------------------------------------------------------------------------------------------------------
>                 Key: DERBY-1696
>                 URL: http://issues.apache.org/jira/browse/DERBY-1696
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL, Store
>    Affects Versions:,,
>            Reporter: Andreas Korneliussen
>         Assigned To: Andreas Korneliussen
>         Attachments: DERBY-1696.diff, DERBY-1696.stat, DERBY-1696v2.diff
> If an application does the following:
>  Statement s = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, 
>                                           ResultSet.CONCUR_UPDATABLE);
>  ResultSet rs = s.executeQuery("select * from t1");
>  rs.afterLast();
>  rs.last();
>  rs.next();
> After doing this in transaction isolation level read-committed/read-uncommitted, the
last row is still locked with an update lock.
> This is detected by running the JUnit testcase ConcurrencyTest.testUpdatePurgedTuple1
in the DerbyNetClient framework.
> (NOTE: the bug is revealed by this test, because the network server does a rs.last()
as the first operation on a scrollable updatable resultset to count number of rows)
> What triggers this bug, seems to be the repositioning of the cursor after the underlying
all records have been inserted into the hashtable from the source scan. When moving off the
result set (to afterLast() or beforeFirst()) no action is done to release the lock of the
current row.

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