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From "A B (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1468) Server returns data when it receives a QRYROWSET value of zero on an OPNQRY, which doesn't follow DRDA protocol.
Date Sat, 01 Jul 2006 00:04:31 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1468?page=comments#action_12418737 ] 

A B commented on DERBY-1468:
----------------------------

> Army could you please see if solves the issue with the ODBC driver? 

I'm not able to run the full set of ODBC tests because the harness on my machine is currently
in a bad state (sigh), but I was able to run the repro that prompted the filing of this issue,
and I have confirmed that with your patch applied the ODBC repro runs as it should.

> Since there is no way I know of to reproduce the bug with the network 
> client driver, I have added a test case to the protocol test which sends 
> an OPNQRY for a scrollable cursor with QRYROWSET=0.

Good thinking--sounds like a great plan.  I ran the test with and without your patch, and
it behaves as you describe.

> EXCSQLSTT should probably have a similar fix for completeness. (A 
> possible way to try to provoke this with the ODBC driver could be to 
> execute a stored procedure that returns a scrollable result set.) 

When I can find the time I will experiment with this.  If this proves to be a problem then
I'll create a separate Jira issue to address it--one that is _not_ considered a regression
of DERBY-822 since, as you said, the relevant code wasn't touched with 822.

Thanks for addressing this so quickly!

> Server returns data when it receives a QRYROWSET value of zero on an OPNQRY, which doesn't
follow DRDA protocol.
> ----------------------------------------------------------------------------------------------------------------
>
>          Key: DERBY-1468
>          URL: http://issues.apache.org/jira/browse/DERBY-1468
>      Project: Derby
>         Type: Bug

>   Components: Network Server
>     Versions: 10.2.0.0
>     Reporter: A B
>     Assignee: Knut Anders Hatlen
>  Attachments: derby-1468-v1.diff, derby-1468-v1.stat
>
> When a client sends a QRYROWSET value of zero to the server, DRDA indicates that the
server should not return any rows.  But the current Derby Server treats a qryrowset value
of 0 (zero) the same as it does a value of 1 (one) and thus performs pre-fetching (as of DERBY-822),
which it shouldn't do.
> As a result, clients that send a QRYROWSET of 0 and do not expect data could see unexpected
results--for example, the DB2 ODBC driver will return the first row of data twice for scrollable
cursors because of this issue.
> Relevant discussion:
> http://article.gmane.org/gmane.comp.apache.db.derby.devel/22659
> Some quotes from DRDA manuals:
> 1) DRDA Manual v3 for OPNQRY:
> The qryrowset parameter specifies whether a rowset of rows is to be returned with the
command.  This is only honored for non-dynamic scrollable cursors (QRYATTSNS not equal to
QRYSNSDYN) and for non-scrollable cursors conforming to the limited block query protocol.
 The target server fetches no more than the requested number of rows. It may fetch fewer rows
if it is restricted by extra query block limits, or if a fetch operation results in a negative
SQLSTATE or an SQLSTATE of 02000.
> 2) Page 698 of V.3 says:
> A QRYROWSET value of zero on the OPNQRY and EXCSQLSTT commands instructs the server to
return no rows with the OPNQRYRM for the cursor or result set. A QRYROWSET value of zero on
the CNTQRY command is invalid for non-rowset cursors and results in the application server
generating a SYNTAXRM with a SYNERRCD value of '15'x (reserved value not allowed).

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