🚀 go-pugleaf

On 28 Oct 2002 05:51:52 -0700, Helcio Mayor wrote:

>Dear all,
>I have to say that this newgroup is great because always there are altruistic people prompt to help, and I am very content and
>greatfull to all.
>
>Well, I think I have posted similar question but maybe was not clear enough. 
>Is it possible to call a method or set a property on a query that takes long to return so that it returns ?
>If the user chooses to terminate the application, the only option
>I have is to kill the Thread that keeps the TADOQuery, but it eventually crashes the main process.

I have experimented, and I've determined that using ADO leaves you pretty
much no good option for cancelling queries.

If you use a server cursor, the query can't be cancelled, period.  If you put
it on a second thread, and try to kill it, the kill call will block for the
same amount of time that it would take the search to complete - in other
words, ADO has some hooks into the OS which prevent it from behaving
properly.

If you use a client cursor, you can call Recordset->Cancel(), which will work
fine for an unsorted query.  For a sorted query, it will block for about as
long as the query would take, sans returning the sorted results - in other
words, it's obviously completing the query and sorting it before
acknowledging that it was told to stop.  Another downside to the client
cursor is that large result sets take up big chunks of memory.

In general, ADO is not programmer-friendly, and as a direct consequence, not
user friendly, either.

But it's the only way to use Access 2000 or XP, and Access is still (most
unfortunately) the only portable desktop database system.


--
 - Mike

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