Re: Conditional Adding to a Table

You could use a LOCK TABLE statement to gain an exclusive lock, but a better approach is probably to put a unique
constrainton whatever your check is and then just attempt the INSERT. 

Hope this helps a little....


Allan.

Glenn Sullivan wrote:

> Greetings,
>
> I need to check a table to see if an item already exist in the table.
> It if does not, then I want to add it.  Unfortunately, multiple processes
> (Solaris system) can be running at the same time.  Sometimes, one process
> checks to see if an item exist and it does not. At the same time another
> process checks to see if the same item exist and it does not.  Then both,
> add the item to the table.  This is, of course, not what I want.
>
> I cannot seem to figure out how to do a conditional test to do something
> like this.  If I could, then the whole operation could fit in one transaction
> with locking.
>
> Any ideas?
>
> Thanks,
> Glenn
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
>     (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)