Cancelled query continues to run?

[Michael75]

We had a small incident today. A developer here is creating a FM model and reports against a Sybase IQ datamart, using 10.2.2 & DQM. In his own words, this is what he did:

1)   Run report
2)   Report does not provide data after 2' so I cancelled it
3)   Report cancellation keeps hanging/not responding : so I closed window via task manager

According to our DBA, the query continued to run for over an hour, and retrieved many millions of rows, representing 1.5GB of data  :o

I know that cancelling the execution of a report can sometimes be instantaneous, and at other times very slow to take effect, though I don't know what factors influence this.

Is there anything we can learn from this? Can anyone give some guidance?

Thx
Michael

[Yizi]

Do you have a multi dispatcher environment?
Have you checked the logs for time it was cancelled. Most likely the cancel command did not reach the destination therefore it wasn't cancelled. I've seen this happen when the user isn't patient ...  ::)

[MFGF]

Do you have a multi dispatcher environment?
Have you checked the logs for time it was cancelled. Most likely the cancel command did not reach the destination therefore it wasn't cancelled. I've seen this happen when the user isn't patient ...  ::)

A Cancel command sends an Absolute Affinity request - ie one that is destined for a specific report server process. You wouldn't want the request load-balancing to a different report server, or else the wrong report would be cancelled - therefore it has to be an Absolute Affinity request. If the report server is currently full doing other stuff, the request gets queued until the report server has a connection free to handle it. If the browser session was killed before the kill request could be taken from the queue, then it's likely the kill request got ignored.

That's my guess here :)

Cheers!

MF.

[Michael75]

Thanks Yizi and MFGF!

Do you have a multi dispatcher environment?
Have you checked the logs for time it was cancelled....

@Yizi
Due to a new job I'm not familiar with the environment, and have limited rights. I'm told that in our Dev env where this occurred, we have two CM servers and one Appl tier server. Does that answer your question?
Our admin checked the logs for the time period concerned, and saw nothing out of the ordinary. But he hasn't been long in this role. Is there something specific he should be looking for?

@MFGF
Your answer makes perfect sense :)

Thx
Michael

[the6campbells]

#1 - contact IBM Cognos support re 10.2.2 related fix packs and cancel requets
#2 - call Sybase and ask them if a JDBC ResultSet object is closed before all rows are read, does their client continue to read the remaining rows.

[sunosoft]

I got little confused here....cancelling report on cognos connection will really cancel a query triggered by it on DB ? I believe NO.

I think query will continue to execute on DB but result will not be transferred to Cognos server because target process will not be available as it has already cancelled on cognos level. This is what my guess for this particular stuff :-) . So once u cancel report here and if you know generated query is going to fetch huge data you should contact DBA and ask him/her to cancel that particular query.

[the6campbells]

From a query engine perspective, if a cancel event occurs in Cognos BI, it will issue a cancel request to the RDBMS client driver. If the query had finished executing and as data is being received, a similar cancel event in Cognos BI will result in the RDBMS driver being told to close the result sets (cursors) that are open.