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subhaoviya
Posting Yak Master
135 Posts |
 Posted - 2014-05-20 : 07:07:16
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| Hi, I am having main table T1 having 50 million records init, having another table t2 having 3000 records. T1: C1, C2, C3, c4, c5T2: C1, C2I need to match C1 between both tables and if matched need to update C2 else need to insert record into T1. Even when I used merge statement for this due to heavy data collection in T1. query taking more than 3 hours to execute.not only this T2 I have having 6 more tables having some thousand of records to match with T1 and update other columns init.please help me to optimise this action.ThanksSubha |
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bandi
Master Smack Fu Yak Hacker
2242 Posts |
Posted - 2014-05-20 : 07:34:54
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| While executing the MERGE, enable execution plan (Ctrl + M). Have a look at the index usage and which one is costliest operation.. NOTE: Find out any Missing Indexes on those tables--Chandu |
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ScottPletcher
Aged Yak Warrior
550 Posts |
Posted - 2014-05-20 : 17:03:20
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| Best for this process would be for T1 to be clustered on C1; can't say overall if that is best for the table.MERGE often has performance issues. You'd almost certainly be better off doing an UPDATE followed by an INSERT. |
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big table lookup