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From: Frederik Engelen on 1 Jun 2010 09:41
On Jun 1, 2:48 pm, Gregor Kovač <gregor.ko...(a)mikropis.si> wrote:
> Hi!
>
> Thanks for the feedback.
> I am/was under the impression that IMPORT does a exclusive table lock. How
> can I do parallel import then?
>
> Best regards,
>         Kovi
>
>
>
>
>
> Serge Rielau wrote:
> > Kovi,
>
> > Feedback from backstage:
>
> > Load is faster than import in most of cases.   Better to describe cases
> > where import can be faster:
>
> > 1) Correct about  small files.  Load has a startup and shutdown cost.
> > 2) Parallel import can catch up and beat load (ie, running lots of
> > parallel import command with the data split already) specifically when
> > XML is in the table.
>
> > More indexes will likely hurt import more than load, because the data
> > isn't sorted, and the index inserts are a single row at a time.  Load
> > will be faster with larger files regardless of the number of indexes
>
> --
> -~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
> | Gregor Kovac |    Gregor.Ko...(a)mikropis.si      |
> |              |    http://kovica.blogspot.com |
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> |  In A World Without Fences Who Needs Gates?   |
> |              Experience Linux.                |
> -~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-

From the 'Data Movement Utilities Guide and Reference' e-book:

"Import acquires either an exclusive (X) lock or a nonexclusive (IX)
lock on existing target tables, depending on whether you allow
concurrent access to the table."

Did you already download this book? As you seem interested in the
matter, I really think you should take a look at it.

--
Frederik Engelen
RealDolmen
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