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tarun_bhardwaj
New User
Joined: 18 Jul 2003 Posts: 39 Location: delhi
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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:
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LOAD DATA REPLACE LOG NO INDDN SYSREC00 NOCOPYPEND INTO TABLE ABC.TABLE1;
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Can anyone please help me understand why the performance must have degraded ?
Thanks in advance ! |
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dejunzhu
Active User
Joined: 08 May 2008 Posts: 390 Location: China
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Which version of DB2 you are using?
If DB2 v9, you can use TRUNCATE statement. |
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dejunzhu
Active User
Joined: 08 May 2008 Posts: 390 Location: China
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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
Senior Member
Joined: 11 Aug 2009 Posts: 1281 Location: Belgium
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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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