RE: ORA-01555 Mystery (Help)

Precisely the point I was trying to make, when I put the question if it was a normal select, or if it was within a PL/SQL block? The myth is that snapshot too old happens only when some other transaction was in the process of performing an DML on a table, when you did a select on it. It can happen for other reasons too. Search on Metalink for "Delayed block cleanouts" and "fetch across commits".

Raj

"Baker, Barbara" <bbaker_at_denvernewspaperagency.com>@fatcity.com on 01/25/2002 11:52:05 AM

Please respond to ORACLE-L_at_fatcity.com

Sent by: root_at_fatcity.com

To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> cc:

I have a batch job that does this consistently. It's the only job in the database; it sets the transaction to a hugh rollback segment. And it eats its own tail.

Depending on how the job is written, it may need a read consistent view itself (as opposed to some other query in the database needing that read consistent view.) In that case, it may well go try to read its own rollback segment, only to find that it's been overwritten. (Oddly enough, even when there's plenty of space to extend the rollback, Oracle will decide
to overwrite the original rollback segments rather than extend if it thinks it doesn't need those segments any more.)

I'd strongly suggest you get the stuff from Steve Adams' ixora site that places an uncommitted transaction in your rollback segments for the length of the run. This will guarantee that the rollback segments don't get overwritten.
Good luck!

Barb

> ----------
> From: Walter K[SMTP:alden14004_at_yahoo.com]
> Reply To: ORACLE-L_at_fatcity.com
> Sent: Friday, January 25, 2002 9:15 AM
> To: Multiple recipients of list ORACLE-L
> Subject: ORA-01555 Mystery (Help)
>
> Hi,
>
> A user in our data warehousing group is running into
> the old ORA-01555 (snapshot too old) error every time
> she runs a massive (20 million rows) select against
> one table via a view. I confirmed that the view only
> translates to the one table.
>
> The user swears that no one would be making any
> updates/deletes to the table she is selecting from. I
> suggested she lock the table in exclusive mode, prior
> to running her massive select to guarantee no one else
> could change the data in the table and cause the
> triggering of the 1555 error. Locking the table was a
> viable option because it's a staging table in the
> warehouse itself. She locked the table in exclusive
> mode last night and it locked; fired off her query,
> and it failed 5 hours later with the 1555 error again.
>
> I'm stumped on this. I just don't see how this is
> possible. Any suggestions?
>
> Thanks!!!
> -w
>
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Author: 
  INET: Rajesh.Rao_at_chase.com

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