Time wait - line lock - data concurrency - Solved with workaround

Question

Hi.
A session inserts a line in a table and it does not make commit.
Another session makes another insert in the same table, with the same value for primary key and, because of the Lock, it is waiting for one commit or rollback of the first session, and only after this it's get a error message.
Exists some way to make with that the error message is shown immediately, without waiting for commit or rollback of the other session (first session)?
PS.:
But I need to continue with READ COMMITTED (statement) isolation level, because the SERIALIZABLE (transaction) would generate many locks.
Message was edited by:
ARF
Message was edited by:
ARF

Answer 1

Using a sequence for a PK will not solve your problem since I believe that you would still need a unique index (perhaps unique constraint) on the business value to prevent duplicates. Using a sequenced generated value for the PK would just move the problem to this second index unless the current PK is just a sequential number in which case why can't the value have gaps?
I know a system that uses a sequence generated value for its invoice numbers assigned at shipping time. There are gaps. When the auditors questioned it (after 8 years of being this way) it was pointed out that a sequential set of invoice numbers does not prove that an invoice that should have been generated was not skipped or that the invoices themselver are complete. The real audit trail is the report that show for every item on a sales order every item was shipped and invoiced. The cross reference report is the validation. The invoice numbers are meaningless. Sequential numbers are a false sense of security.
Possible alternates are to use a sequence as the PK (or a UK) and to update a second key column sequentially via batch (update table in sequence value order assigning sequential value via function which adds one to previous value on each use) Since only one process will perform the assignment there will be no gaps.
HTH -- Mark D Powell --