Qt-interest Archive, January 2008
How to verify opened database connections?
Message 1 in thread
I've created connection pool mechanism to maintain the opened database
connections and a procedure to use/release connections, some time connection
pool might hold bad connections due to db or network issues or some other
reasons, so I need to remove such bad connections from the pool and to do
that I am trying to add cleanup code to be executed at regular interval.
Question here is: What is the best method to determine the bad connection in
the pool?
I would like to do without executing a SQL query, is there a quick method to
verify the db connection using the connection object?
If not what is the correct/best method to verify the opened connections
(without affecting the application performance)?
Thanks,
Bab
Message 2 in thread
On torsdag den 3. Januar 2008, Babu Sathyanarayana wrote:
> I've created connection pool mechanism to maintain the opened database
> connections and a procedure to use/release connections, some time
> connection pool might hold bad connections due to db or network issues or
> some other reasons, so I need to remove such bad connections from the pool
> and to do that I am trying to add cleanup code to be executed at regular
> interval.
>
> Question here is: What is the best method to determine the bad connection
> in the pool?
>
> I would like to do without executing a SQL query, is there a quick method
> to verify the db connection using the connection object?
> If not what is the correct/best method to verify the opened connections
> (without affecting the application performance)?
I don't think there is a way to do it without running an SQL query. There
might be driver specific ways to do it for some of the drivers, but I would
stay clear of those.
You could make a stored procedure called ping that returns an empty result
set. That shouldn't affect performance in any way. But that's still a ping,
not a signal you get.
The correct approach would be to make your queries robust and automatically
try reconnecting after loosing the connection. Even if you did get a signal
on connection lost, you will have race conditions between these and executing
queries.
Bo.
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