Re: long to clob conversion redo size and new table size

From: joel garry <joel-garry_at_home.com>
Date: Mon, 27 Jul 2009 14:51:07 -0700 (PDT)
Message-ID: <d525cba2-3fca-462b-a3c3-bf57135ae84d_at_v23g2000pro.googlegroups.com>



On Jul 27, 1:53 pm, Grzegorz <grzegor..._at_interia.pl> wrote:
> joel garry pisze:
>
>
>
> > On Jul 27, 12:16 pm, Grzegorz <grzegor..._at_interia.pl> wrote:
> >> Mark D Powell pisze:
>
> >>> On Jul 27, 12:19 pm, Grzegorz <grzegor..._at_interia.pl> wrote:
> >>>> Hi,
> >>>>         I've got 300GB table t1 with 2 columns:
> >>>> id number primary key,
> >>>> some_data long
> >>>> currently 70 mln rows.
> >>>> When I'm doing to_lob conversion via:
> >>>> insert /*+ APPEND NOLOGGING */ into t2 select id, to_lob(some_data)
> >>>> some_data from t1 where id between 1 and 2222222;
> >>>> table t2 clob is defined as 8kb chunk in MSSM tablespace (uniform size 1M)
> >>>> a 63MB redolog is switched every 18 seconds.
> >>>> My question is what is in redo ?
> >>>> The only think which comes to my mind is lob index maintenance but
> >>>> is that true ? Database is 9.2.0.8 and NOARCHOVELPG mode.
> >>>> Second question :
> >>>> How to minimize ne wtable (t2) size (table is insert/select only).
> >>>> Regards.
> >>>> Grzegorz
> >>> LOB data is forward recoverable just like any other data.  The LOB
> >>> inserts are being logged.
> >> Even with NOLOGGING hint ?
> >> How to minimize redo size in that case ?
>
> > Oh I forgot to add, you can set the index unusable and alter session
> > skip_unusable_indexes to true, unless it is unique.
>
> Are You sure I can make unusable lob-index (this is the only index I've
> got)?
> Is that supported ?
> Regards.
> GG

I'm not sure of anything, all I know is what I read in the papers :-)

As an extremely frustrating COBOL teacher I had many years ago, would say in response to just about any question... "Try it."

jg

--
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Received on Mon Jul 27 2009 - 16:51:07 CDT

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