Re: ** table with clob slow

Hello,
I had the same issue about a couple of months ago. We have 1 table that's
80GB with a CLOB column and its all documents and images.
I could not use TTS as the character set was changing from single to a
double byte character set and exp imp was the only option I had.

The export took about 5 hours and import about 34 hours !!!

Since this was not going to work, I had an id column in the table and based
on the distribution I generated multiple export files with almost equal ID
ranges using the query clause. I also did the import in parallel ( 4 files
at a time, had 10 files). The export was done in about 90 mins and the
import took about 6 hours....

So if you can break the export into multiple export files using the query
parameter, you can run the imports in parallel on the target and that should
be faster

Thanks
Madhavan


On 6/23/06, Leng Kaing <Leng.Kaing@xxxxxxxxxxx> wrote: 

  Hi,



If you think exporting CLOBs are slow, wait till you import! It's much
much slower.



During imports, depending on the size of your clob column, you may be able
to get away with COMMIT=N. I've found this to be much faster than COMMIT=Y.
However, it means that you must have a LARGE undo retention and tablespace,
otherwise your import will fail.



The other trick we've found is that even though we have clob columns
defined in the tables, they are actually empty. So doing a "sql unload" and
sqlload without the clob columns will cut down your times.



HTH,



Leng.

-------------------------



Date: Thu, 22 Jun 2006 19:35:23 -0700 (PDT)

From: A Joshi <ajoshi977@xxxxxxxxx>

Subject: ** table with clob slow



Hi,

     We have a big table and it has one field with CLOB datatype. Doing an
export on this table is very slow. I have tried with different buffer sizes
of 2MB - 250MB. It is still slow. Any way to speed up export and other
operations on the table like update,delete. Thanks for your help.





------------------------------------------------------------------

Leng Kaing

Senior Oracle DBA

Hansen Technologies; 2 Frederick St; Doncaster 3108

Ph: +61-3-9840-3832


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