Re: how synchronous is Oracle?

"Robert A.M. van Lopik" <lopik_at_mail.telepac.pt> wrote in message news:<3e66fee5$0$10173$a729d347_at_news.telepac.pt>...
> Consider the following scenario:
> I have two processes, A and B. process A logs on to the database, inserts a
> record into a table, logs of and signals (one way or another) process B.
> Process B was already logged on and does a select that should retrieve the
> record just inserted.
> The question is: does Oracle guarantee that committed inserts are
> "immediately" visible to other users, or is there a possibility, e.g. on a
> heavily loaded system, that proces B will not retrieve the record, although
> it will see it at a somewhat later time?
>
> I found a thread in this forum about serializability around 1999, but that
> was too theoretical for my liking. For now I just would like to rule out the
> possibility that records would not be immediately visible, or learn how to
> make this happen if the guarantee is not there.
>
> B.T.W. The concrete question is about Oracle Version 8.1.7
>
> Thanks,
> Rob van Lopik

Committed inserts are immediately visible to all users with no delay, so your process should work without problems.

The article on serialisability referred to serialiasiable transactions, where process A updates a record, then process B wants to update that same record. This is not the same situation; serialisability ensures that no matter what order a series of transactions takes the end result is the same. Your scenario is completely different.

David Fitzjarrell Received on Thu Mar 06 2003 - 11:10:48 CST