Re: Q:Serializability and Row Level Locking

droth_at_adaptron.com (CaseMan) wrote in message news:<3cc4bfc6.5877160_at_netnews.attbi.com>...
> SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
>
> When Oracle is running in the default "Read Committed" isolation
> level,
> readers do not block writers, writers do not block readers and writers
> do not block each other unless they attemp to change the same row.
>
> SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
>
> How are writers effected when a query is running "Serializable".

Writers are not affected.

> How are readers effected when an insert/update/delete is running
> "Serializable".

Readers would read information as at beginning of transction. In short, set transaction isolation level serializable is similar to set transaction read only. The difference: you can actually update database in serializable mode and transaction starts at first update operation instead of set transaction statement.
I might be wrong in details. If you want to get accurate information, refer to Oracle Server Concepts and Oracle SQL Reference.

>
> Thanks
>
> Dave
Received on Tue Apr 23 2002 - 10:04:57 CDT