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On 1/10/11 12:57 PM, Bryce Martin wrote:
Won't the multiple select statement have a negative impact on
performance compared to a list of predetermined values?

"Schutte, Michael Don01/10/2011 03:36 PM wrote:

Change this to...

Select Cast(rncust As Numeric(6,0)),
Cast(rnseq As Numeric(4,0)),
Cast(rntype As Numeric(2,0)),
rnword1, rnword2, rnword3, rnword4, rnword5
From rcm002pf
Where rnword1 in (select WorkKey1 from WorkTable1)


The real issue for performance impact would be for the /maintenance/ on the work table [i.e. drop, create, open, insert, clear...] rather than the much smaller impact of running and using the result of the subselect. If the input string is as easily parsed as the example, then I believe a recursive CTE breaking the string into rows [of a true temporary file as created by the database scoped to that SELECT] would perform noticeably faster than using a user-created work table.

Regards, Chuck

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