TUNING QUERIES
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I have a 4 parts of query in the first 3 parts iam inserting the output into a temporary tables(by using select into) .The 4th part of query is getting the data from these temporary tables .The first 3 parts are execuing very fast but 4th part is taking very late.When i saw the query execution plan HASMATCH/INNER JOIN IS TAKING 48 %COST,and other table clusterindex scan is taking 35%.
How to tune this query?
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The tablescan is one obvious target for tuning. Check for appropriate indexing.
Another area is temptables. Are they necessary? .. really?
Hashjoins may be 'slow', but this is really an 'it depends' issue.
Other thoughts.. How slow is 'slow'? ie From where to where are you looking to tune?
The percentages has nothing to do with actual performance, they are just indicators of the relative distribution of work done within the plan. They do however serve as pointer where to look for tuning.
What's the volume of data involved?
Could you post the actual query? (you may alter names etc to protect the innocents
)...more info will be needed, so tell us all you can, preferrably with some illustrating example as well.
/Kenneth
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