How to cancel a long-running Database operation?

Question

Currently working with Oracle, but will also need a solution for MS SQL.

I have a GUI that allows users to generate SQL that will be executed on the database. This

Answer 1

I think the best solution seems to kill sessions via monitoring table.

With Oracle you can make it as says Burnsys

In Firebird 2.5 it will looks the same

I hope something similar exist in Ms SQL

Answer 2

What about opening a new connection to the database, login in as sysdba and sending a "ALTER SYSTEM KILL SESSION 'sid,serial#' IMMEDIATE" command specifying the SID of the process you want to terminate.

To get the sessionID: select sid from v$mystat where rownum = 1

To get Serial#: select sid, serial# from v$session where sid = :SID

http://www.oracle-base.com/articles/misc/KillingOracleSessions.php

EDIT: WW idea for not Login as sysdba here: http://forums.oracle.com/forums/thread.jspa?threadID=620578

Answer 3

KILL SESSION was the only working way for me to cancel the long running query. I am using the managed oracle provided and OracleCommand.Cancel() works some times but usually it's not working. Also OracleCommand.CommandTimeout is not respected according to my tests. Some time ago when i was using the unmanaged oracle provided i managed to cancel commands but not any more with the managed one. Any way killing the session was the only option. The query is not running on the UI thread but on a seperate thread. The cancel command is send from the UI thread. Its a little more complex because the application uses a middletier using WCF but at the end of the day i am killing the session. Of cource when running the query i have to find and save the session in order to kill it if necessary. There are many ways to find sid and serial# in order to kill the oracle session and i want waste your time explaining something you already know.

Answer 4

I am pretty sure it is possible- we use TOAD for Oracle, and it lets you cancel long-running queries, as described here. I'm not sure how they do it though.

Answer 5

I also noticed command.Cancel() doesn't really abort the command. What worked for me is closing the connection (rollback transaction if you use one) when the user aborts. This will raise an exception in your background thread while the command is executing, so you have to catch it and check the CancellationPending property there and not rethrow the exception in that case...

// When aborting
worker.CancelAsync();
command.Connection.Close();

// In your DoWork event handler
...
catch (Exception)
{
    if (worker.CancellationPending)
    {
        e.Cancel = true;
        return;
    }
    else
    {
        throw;
    }
}

// And in your RunWorkerCompleted event handler
if (e.Error == null && !e.Cancelled)
{
    ...
}

Answer 6

Oracle introduced ALTER SYSTEM CANCEL SQL in 18c. You would need to add some kind of comment with UID to your SQL and then look for it something like this

SELECT S.SID||','||S.SERIAL#
                    FROM GV$SESSION S, V$SQL Q
                    WHERE S.USERNAME IS NOT NULL
                    AND S.STATUS = 'ACTIVE'
                    AND S.SQL_ID IS NOT NULL
                    AND Q.SQL_ID = S.SQL_ID
                    and sql_text like '%{queryId}%'

And then run another operation from .NET ALTER SYSTEM CANCEL SQL 'SID, SERIAL'