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LOAD REPLACE with DUMMY performance

 
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tarun_bhardwaj

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Joined: 18 Jul 2003
Posts: 39
Location: delhi

PostPosted: Tue Sep 01, 2009 5:00 pm    Post subject: LOAD REPLACE with DUMMY performance
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Hi,

I had earlier read that LOAD REPLACE with DUMMY works faster as compared to DELETE * from table incase the volume of data is very large.

In our shop(with 300+ tablespaces with each tablespace housing one table), DELETE * from table was earlier being used. To improve the performance, I tried to use a LOAD REPLACE with DUMMY but to my surprise the job ran at a much slower speed than what it earlier used to run with. I ran the original job (the one with DELETE * from table) and the one with my changes (LOAD REPLACE with DUMMY) in parallel on two different databases. The original job completed in 8 minutes whereas the one with my changes finished in 35 minutes.

Here is one of the LOAD statements that I provided in SYSIN:
Code:
LOAD DATA REPLACE LOG NO INDDN SYSREC00 NOCOPYPEND INTO TABLE ABC.TABLE1;
                                   


Can anyone please help me understand why the performance must have degraded ?

Thanks in advance !
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dejunzhu

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Joined: 08 May 2008
Posts: 390
Location: China

PostPosted: Tue Sep 01, 2009 7:33 pm    Post subject:
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Which version of DB2 you are using?
If DB2 v9, you can use TRUNCATE statement.
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dejunzhu

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Joined: 08 May 2008
Posts: 390
Location: China

PostPosted: Tue Sep 01, 2009 7:37 pm    Post subject:
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If you insist on using LOAD REPLACE with DUMMY , perhaps you should put the log of your loading job here. We can analyse the performance issue from the log.
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GuyC

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Joined: 11 Aug 2009
Posts: 1281
Location: Belgium

PostPosted: Wed Sep 02, 2009 3:02 pm    Post subject:
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just a guess : check your DSNDBD VSAMs

Maybe LOAD REPLACE cleans up your VSAM (extents, extra VSAMS) and delete * doesn't.
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