Compare 2 datasets and output delta in one TSQL statement
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Comments posted to this topic are about the item Compare 2 datasets and output delta in one TSQL statement
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Where's the code?
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Any idea on how well this scales, or its performance versus using a full join between the two tables with a WHERE clause where either side is NULL?
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OK, now the code is showing. Thanks.
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Hi,
As with any unbalanced compare, the performance varies.
Just compare this method with use your favorite compare and look closely at the execution plan
In my query close to 50% of the time is spent reading the 2 source tables using a clustered index scan, which is the most efficient way to read the ENTIRE table content.
The Merge join that does the actual compare work is only 19 % of the time
The rest: 33%, is spent storing the result.
If you find a more efficient way, i'd be happy to review your code!
Theo
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--Compareandinsertdeltaintotable,inonesqlstatementInsert into #cmpAB([EmpNr_a],[EmpNr_b],[Name_a],[Name_b],[HireDT_a],[HireDT_b],[FireDT_a],[FireDT_b])SELECT a.[EmpNr],b.[EmpNr],a.[Name] , b.[Name],a.[HireDT] , b.[HireDT] , a.[FireDT] , b.[FireDT]FROM #tblA a INNER JOIN #tblB bON a.[EmpNr] = b.[EmpNr]WHERE( a.[Name] <> b.[Name] OR a.[HireDT] <> b.[HireDT] OR a.[FireDT] <> b.[FireDT])UNIONSELECT a.[EmpNr],b.[EmpNr],a.[Name] , b.[Name],a.[HireDT] , b.[HireDT] , a.[FireDT] , b.[FireDT]FROM #tblA a FULL OUTER JOIN #tblB bON a.[EmpNr] = b.[EmpNr]where (a.[EmpNr] IS NULL OR b.[EmpNr] IS NULL)--ThanksMitesh OswalRegards,
Mitesh OSwal
+918698619998 -
Thanks for the script.
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