Re: CTAS for tables with big lob segment (out of line) very slow

Hi

If you get snapshot too old with LOB you should get something like

ORA-22924 snapshot too old folowed by
ORA-01555 snapshot tool old
**
Regards
**

On 8/7/06, Zhu,Chao <zhuchao_at_gmail.com> wrote:
>
> I have workaround the issue with:
>
> alter table move subpartition xxx lob ()... parallel 4 nologging;
>
> Using this approach, moving the lob table is taking 10-15 minutes, and
> with CTAS/exchange, the CTAS is using 2-3 hours.
> I did not do the actual table move, I moved the test table which I get
> from CTAS from subpartition of the original table.
>
> We did not use ASSM tablespace. We use traditional freelist management
> within LMT tablespace;
>
> I am still trying to figure out why CTAS and move has such huge
> performance difference;
>
> PCTVERSION can help reduce the snapshot too old issue for LOB, but it
> comes with more space usage.
>
> And My question is not how to resolve the snapshot too old, but knowing,
> whether it is non-lob data causing snapshot too old, or the LOB segmetn
> causing snapshot too old. I have not figured it out yet.
>
> Insert /*+ append**/ provide the same performance as CTAS, my colleague
> did the test with similar performance as CTAS.
>
> On 8/7/06, Nuno Souto <dbvision_at_iinet.net.au> wrote:
>
> > Hemant K Chitale wrote,on my timestamp of 6/08/2006 2:53 PM:
>
>
> Cheers
> Nuno Souto
> in sunny Sydney, Australia
> dbvision_at_iinet.net.au
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>
>
>
> --
> Regards
> Zhu Chao
> www.cnoug.org
>

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