Re: Faster imports

If this is for a one-off rebuild type of activity, you might risk taking advantage of the

    _disable_logging = true
parameter in init.ora.

Take a full cold backup of the database first, as if you have anything other than a perfect normal shutdown in this mode there is NO option for recovery.

With _disable_logging = true, the call to write redo is still made, but the actual file-write it not made.

You will still need to make the redo files extremely large as checkpoints still
occur when the redo logs are nominally
full.

Also - reduce db_files to a minimum to keep the db writer batch size down so that dbwr keeps dribbling I/O out rather than freezing the system to write large chunks.

Set sort_direct_writes = true and sort_area_size to 4M to 10M, sort_write_buffers = 4 and sort_write_buffer_size = 65536 to get the best possible speed from index creation.

I assume you are importing without (most) indexes, as these can be created afterwards in batches rather than one at a time.

Try to make tables and indexes parallel before you export so that any index creation that occurs at import time uses the parallel query option.

You may be able to relink import (imp) to be a single task executable (rather than having a shadow). This feature has been removed from recent versions of Oracle, but can improve performance by a few percent.

How about doing multiple exports, then you can do multiple concurrent imports.

--

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

rob van laarhoven wrote in message
<948298454.768679_at_newsreader1.wirehub.nl>...
>> The incremental commits didn't do much for me, but using nologging
>> descreased a 3hr import to 30minutes.
>>
>While reading about this suggestion I found this on metallink :
>
>The NOLOGGING attribute effects Direct Load Inserts such as SQL*Loader
>direct path load and parallel insert. Unfortunately, this is not a feature
>of Import.
>
>Is this a new feature, imports using the nologging attribute?
>
>Rob.
>
>
>
Received on Wed Jan 19 2000 - 11:22:03 CST