| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> Re: parallel processes and hot blocks
> Direct-path or APPEND insertions executing in parallel do not share
blocks.
> No chance for block-level contention because each process is filling its
own
> "temporary" segment.
Agreed, but this works like that only on a single insert with PARALLEL clause. If you're using insert APPEND in regular noparallel sessions, then the table is locked in shared mode for data consistency reasons until transaction is committed (Oracle moves HWM marker to the new location only after commit).
If you won't use APPEND and use just lots of sessions doing array inserts, you should define FREELISTS of your table to a number of concurrent inserts. Depending on number of sessions you might start getting contention on segment header block, if you get it then you have to decide whether to partition your table, use freelist groups or go with ASSM. Using freelist groups can be tricky (free block lists in one freelist group can't be seen by processes which are mapped to another freelist group block), so before using them, some thought is needed.
Also, you might get HWM enqueue contention, in this case partitioning helps (or ASSM somewhat, too).
Tanel.
>
>
> on 7/9/04 12:32 PM, ryan.gaffuri_at_comcast.net at ryan.gaffuri_at_comcast.net
> wrote:
>
> > I have to do a data migration. I am thinking of breaking it into pieces
and
> > running a larger number of array inserts at once into the same table. If
I use
> > 'append', will I run into issues with hotblocks on the insert side if I
am
> > doing 10-20 array inserts into the same table at the same time?
>
> ----------------------------------------------------------------
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> ----------------------------------------------------------------
> To unsubscribe send email to: oracle-l-request_at_freelists.org
> put 'unsubscribe' in the subject line.
> --
> Archives are at http://www.freelists.org/archives/oracle-l/
> FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
> -----------------------------------------------------------------
>
-- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------Received on Sat Jul 10 2004 - 06:14:25 CDT
 |
 |