use of distinct and group by.

Question

use of distinct and group by.

nitin.varshney

SSC Eights!

Points: 948
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October 10, 2012 at 6:08 am

#269160

if i am selecting the some distince records from the large data sets, which is better to use for performence point of view : distinct cluase in select statement or group by clause without some aggregate function.

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Chandra Sekhara Vyas Dhara SSChampion Points: 10207 More actions · Answer 1

If you want to have distinct values u can use distinct otheriwise you want aggreate values for the columns you need to use group by clause. All that depends on your need of data

nitin.varshney SSC Eights! Points: 948 More actions · Answer 2

actually there is no need to aggregate the some value. only need to identify the distinct records. which also can be possible using the group by clause. so i just want to know which way is better for performence prospects.

Sean Lange SSC Guru Points: 286590 More actions · Answer 3

nitin.varshney (10/10/2012)
actually there is no need to aggregate the some value. only need to identify the distinct records. which also can be possible using the group by clause. so i just want to know which way is better for performence prospects.

Have you tried it and looked at the execution plans for each? They will almost always generate the same plan so there is little to no performance difference. As a general rule if there is aggregate data, use group by. If there is no need for aggregation but you just want unique rows, use distinct.

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