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Re: ORA-1555 snapshot too old: why?

From: EscVector <Junk_at_webthere.com>
Date: 19 Dec 2006 20:34:38 -0800
Message-ID: <1166589278.443330.295640@n67g2000cwd.googlegroups.com>

On Dec 15, 5:26 pm, Chuck <skilover_nos..._at_bluebottle.com> wrote:
> Oracle 9.2.0.7
>
> I got an ORA-1555 snapshot too old today on a export where consistent=y
> was set. The export failed at 6 hrs even though undo_retention was set
> to 8 hours. Querying v$undostat shows that during the time when the
> export was running a total of only 150m of undo was written. The undo
> tablespace is 4g. Why would I get an ora-1555 when undo_retention is set
> plenty high enough, and the undoblks written weren't anywhere near
> maxing out the undo tablespace?
>
> TIA
Do you really need to use export?

Had this problem with a huge marketing database on a really crappy box.  Used db links and CTAS to get around the issue. Would never have completed with export. We were close to 15 hrs+ with exp only to fail on 1555 and only 5hrs with CTAS. The issue was disk contention and process power. The exp was running on the same box as the database, thus causing overhead, and we were limited to local disk in this situation. DB link to fresh clean SAN instances solved the problem. The database had to be running 24/7 so we had few other low-tech data moving options. Received on Tue Dec 19 2006 - 22:34:38 CST

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