Re: C/S Concurrency issue

> UPDATE T set COUNTER = COUNTER+1 where NAME = 'value';
> SELECT MAX(COUNTER) into :my_var FROM T where NAME = 'value';

That's no solution:

Client #1 updates the counter to 100
Client #2 updates the counter to 101
Client #1 selects 101
Client #2 selects 101

oops!

The sequence/serial... solution is best, but it looses points for not being portable.

You could put a unique index on the table being updated/inserted, check for failures and retry, but watch out for deadlocks. Received on Tue May 19 1998 - 20:13:49 CDT