Re: -1555-ORA-01555: snapshot too old: rollback segment number 7 with name "_SYSSMU7$" too small

> So i should extend the undo_retention parameter for example to 28800,
> is correct?

Issue the following query:

SELECT MAX(maxquerylen) FROM v$undostat;

Your UNDO_RETENTION should be larger than this value. And if you know you have a 4 hour batch job, you might want UNDO_RETENTION to be larger than that value.

> extending undo_retention parameter need stop of oracle instance i
> guess...right?

The UNDO_RETENTION parameter is system modifiable.

ALTER SYSTEM SET undo_retention=28800 SCOPE=MEMORY;

If you are using a SPFILE, you will probably want to change scope to BOTH. If you are using a PFILE, then modify your INIT.ORA.

> this change could cause overload on the db and the server?

Increasing your UNDO_RETENTION may cause you to increase your Undo tablespace size. That's about it.

HTH,
Brian

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Brian Peasland
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