Re: Read-only tablespaces and the undo log

"Peter" <peter.paton_at_transdim.com> wrote in news:1108827320.108967.186700_at_c13g2000cwb.googlegroups.com:

> In the past I've received a "snapshot too old" error while executing a
> select statement against a large table. I was told that this was a
> result of the database using the rollback segment (on 8i) to provide
> read consistency on the table. Was that incorrect? (This issue did
> seem to resolve itself when we positioned the table in a read-only
> tablespace.)
>
>

You can get ORA-01555 while doing a SELECT, but only when another session CHANGES data and then does a COMMIT. After the COMMIT Oracle is free to overwrite the data which would provide the SELECT with a read consistent view of the data. My previous point was that the SELECT does not "generate" any undo or redo; however it may try to use what is in the RBS to achive a read consistent view of the data. Placing a table into a readonly TS precludes another session from generating undo segments; hence no ORA-01555 Received on Sat Feb 19 2005 - 10:21:27 CST