Re: By default, LOB store in line or out of line?

  • From: Leyi Kamus Zhang <kamusis@xxxxxxxxx>
  • To: fairlie rego <fairlie_r@xxxxxxxxx>
  • Date: Mon, 23 Apr 2012 22:17:41 +0800

Hi, Fairlie
Our test is with 8 concurrent sessions CTAS over dblink, we transfered 7TB
LOB in 64 hours with "as of scn" flashback query from source database.

Yours 12 concurrent jobs in 9 hours transfered 500GB data or 13TB? I also
tested insert /+*append parallel*/, but the result is far worse than CTAS.
Can you share your test result? Did you test CTAS?

Our migration is painful... the source database has a single table over
7TB, almost LOB, no partition, actively inserted and updated, we have to
use WHERE condition to split the source table into little pieces and have
to use flashback query to get the consistency. The worst experience was
after 20 hours CTAS we got ORA-01555 error, even we have set the UNDO
RETENTION for LOB to 48 hours.

Kamus <kamusis@xxxxxxxxx>

Visit my blog for more :

On Mon, Apr 23, 2012 at 7:10 PM, fairlie rego <fairlie_r@xxxxxxxxx> wrote:

> Approach 2
> ---------
> Insert over a dblink by having 12 concurrent scheduler jobs each working
> on discrete data (as outlined by Tanel below) took less than 9 hours.


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