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Performance issues with concatenation operator [message #369395] Tue, 12 September 2000 14:37 Go to next message
Gerard Vaz
Messages: 9
Registered: September 1999
Junior Member
Is it true that the performance of a query degrades if the columns being selected are concatenated (in my case they are just two columns)? If so, how significant is the degradation?

What about if the columns are indexed?

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Re: Performance issues with concatenation operator [message #369423 is a reply to message #369395] Tue, 19 September 2000 11:39 Go to previous messageGo to next message
Melissa
Messages: 65
Registered: January 2000
Member
When concatenation is used in a query, the indexes are not accessed resulting in full table scans.

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Re: Performance issues with concatenation operator [message #369449 is a reply to message #369395] Fri, 22 September 2000 17:43 Go to previous message
pat
Messages: 27
Registered: September 2000
Junior Member
I think its only a problem if you are doing the concatenation in the where clause

i.e. WHERE COL1 || COL2 = 'XYZ'

If the concatenation is just in the SELECT portion, then it shouldn't affect which indexes are used.

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