Re: ORA 1555 and select count(*)

It didn't.

Assume you are at SCN 10,000 right now, and the original statment needed to see some data as at SCN 5,000, but the rollback segment to get just one block back from SCN 10,000 to 5,000 has been overwritten. - ORA-01555 Snapshot too old

Now you run your count(*) - it wants to see data as at SCN 10,000 because that's
when you started it. No problem.

Similarly, re-running the SAP query, it now wants to see data as at SCN 10,000. again no problem

--

Jonathan Lewis
Yet another Oracle-related web site: www.jlcomp.demon.co.uk

JohannesBavendiek_at_gmx.de wrote in message <7jof95$i5q$1_at_nnrp1.deja.com>...
>I made the experience that the problem with "delayed block cleanout"
>(ORA 1555) was resolved by executing select count(*) ... before
>repeating the step.
>
>Here the description of the situation:
>
>1. a step runs on ora 1555 error in table QCMCOEP (a SAP table for
>conversion use only)
>2. execute select count(*) from QCMCOEP (result: about 19 Mio rows)
>3. repeat of the step runs and ends ok. No other changes made!
>
>This happened in Oracle 8 under AIX.
>The process was a step in a SAP Upgrade, that executed a table
>conversion on table COEP.
>
>How does the simple select count(*) ... change data in rollbacks?
>Can anyone explain this to me?
Received on Thu Jun 10 1999 - 12:25:43 CDT