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?
Yes is does. After the commit calls return, the data is visible to all other sessions.
But, you need the start the select statement after the commit. If you use an older cursor, it will be invisible (visibility is defined on statement level time, e.g. the time you issued the select). What you read about serializeable is a feature that gives you visibility on transaction level, thus avoiding so called phantom reads.

Regards
Stephan Bressler Received on Thu Mar 06 2003 - 03:41:03 CST