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Re: quickest method

From: Mark Richard <mrichard_at_transurban.com.au>
Date: Wed, 14 May 2003 16:00:20 -0800
Message-ID: <F001.00599087.20030514160020@fatcity.com>


Also Carol,

I agree with Jared - my experiences have almost always shown SQL Loader as the fastest way to go when the conditions are right. Obviously there are lots of variables which determine speed (hardware platform, CPU speed, record length, the list goes on) but I have frequently had SQL Loader in the 1+ million records per minute speed range with very little work on my behalf.

When looking into SQL Loader there are a few things which can have a big impact on performance:

  1. Direct loading (similar to insert /*+ append */) - this can be very fast but has some restrictions on when it can be used
  2. Parallel loading (and direct parallel loading)
  3. Removing indexes before using SQL Loader - if you are using conventional loads it can save a lot of time if indexes are removed from the destination table before the load and then recreated.

Regards,

      Mark.

                                                                                                                                      
                      Jared.Still_at_radis                                                                                               
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                      root_at_fatcity.com         Subject:  Re: quickest method                                                          
                                                                                                                                      
                                                                                                                                      
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Carol,

Hands down, SQL Loader is the fastest.

Export/Import is rather slow.

SQL and PL/SQL commands can be on either side of exp/imp, depending on what you are doing and how well the code is written.

e.g. SQL statements are fairly fast, PL/SQL for loops are not. Pl/SQL bulk
processing is fast.

Unless you need the programatic abilities of PL/SQL, use SQL Loader.

Exp/Imp can still be useful, even with SQL Loader. Use exp/imp to build your tables, then the indexes and constraints after the data is loader.

No pat answer as to how to load data, depends on your requirements.

There's probably no point in messing with SQL Loader if the data sets are small, and you can easily export from another database and then import.

If the data is in CSV or flat files though, and/or is very large, SQL Loader
is very fast.

HTH Jared

"Carol Legros" <carol_legros_at_hotmail.com> Sent by: root_at_fatcity.com
 05/14/2003 02:57 PM
 Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc:
        Subject:        quickest method


I'm curious to know whether anyone out there has seen a comparison discussing the pros and cons and/or results of any simulation tests that compare the speed with which data can be loaded into a target database from
a source (database or flat file) using the following 3 methods :

(i) Export (from source), Import (to target)
(ii) SQL*Loader (to target)
(iii) SQL or PL/SQL commands (insert to target)

      using a Database Link between source &
      target

I'm working on a data loading strategy and since there are "many ways to skin a cat", I'm considering these as options. Of course, there are other

criteria that impact the method chosen, but assuming all things are equal
(ie network bandwidth is good, access to both source and target are not an

issue etc.), which of these methods would be quickest ?

Thanks,
Carol



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Received on Wed May 14 2003 - 19:00:20 CDT

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