Re: Why import slow

From the manual - read last line :

http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76955/ch02 .htm#40480
COMMIT
Default: N

Specifies whether Import should commit after each array insert. By default, Import commits only after loading each table, and Import performs a rollback when an error occurs, before continuing with the next object.

If a table has nested table columns or attributes, the contents of the nested tables are imported as separate tables. Therefore, the contents of the nested tables are always committed in a transaction distinct from the transaction used to commit the outer table.

If COMMIT=N and a table is partitioned, each partition and subpartition in the Export file is imported in a separate transaction.

Specifying COMMIT=Y prevents rollback segments from growing inordinately large and improves the performance of large imports. Specifying COMMIT=Y is advisable if the table has a uniqueness constraint. If the import is restarted, any rows that have already been imported are rejected with a nonfatal error.

If a table does not have a uniqueness constraint, Import could produce duplicate rows when you reimport the data.

****For tables containing LONG, LOB, BFILE, REF, ROWID, UROWID, DATE, or type columns, array inserts are not done. If COMMIT=Y, Import commits these tables after each row. ****

-> I remember reading on metalink that it has to be a bug in the documentation - nobody believed DATE showed this kind of effect on the import process. However,

it's still there in the 9R2 docs. I've never experienced slow imports with date columns - I did however had serious performance problems importing longs and lobs when I specified

commit=Y.

The only way to be certain is to use logminer and check the logfiles - but I believe the docs for now ...

"Sybrand Bakker" <gooiditweg_at_nospam.demon.nl> wrote in message news:77m53v4to8sju1hcdl63tamk6ie86gu19c_at_4ax.com...
> On Sat, 25 Jan 2003 15:32:11 GMT, "koert54" <nospam_at_nospam.com> wrote:
>
> >If I'm not mistaking - import performs a commit after each record if a
table
> >contains a long column even if
> >you specify a large buffer ...
>
>
> Just curious: do you have any pertinent evidence? I'm not trying to
> contradict you, but to my knowledge commit=n is a big nono.
>
> Regards
>
>
> Sybrand Bakker, Senior Oracle DBA
>
> To reply remove -verwijderdit from my e-mail address
Received on Sat Jan 25 2003 - 12:59:19 CST