Re: long to clob conversion redo size and new table size
From: Grzegorz <grzegorzof_at_interia.pl>
Date: Mon, 27 Jul 2009 22:53:40 +0200
Message-ID: <h4l44n$8qb$1_at_news.task.gda.pl>
joel garry pisze:
>> 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 ?
Date: Mon, 27 Jul 2009 22:53:40 +0200
Message-ID: <h4l44n$8qb$1_at_news.task.gda.pl>
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
Received on Mon Jul 27 2009 - 15:53:40 CDT