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az_maverick 24 posts Joined 03/09
20 Aug 2009
Difference between select * from table & select individual columns from table

Hello all, I am having trouble understanding difference select * from TABLE X or select a , b, c ( columns) from table X ( same table ) above.I was wondering if someone actually knows what is the difference at the Teradata DB Architecture level.Thanks,Aditi

pawan0608 101 posts Joined 12/07
29 Sep 2009

There would be slight performance improvement when you use explicit list of columns in SELECT stmt, instead of having ‘*’, but I don’t think there is any difference at DB Architecture level

Balamurugan B 81 posts Joined 09/07
29 Sep 2009

Hi,AFAIK there will not be any performance difference between "select * " and "select column_lists", since the optimizer will generate same plan for both the query.Regards,Balamurugan


rediff123 14 posts Joined 02/09
30 Sep 2009

You can use sel top10* from table to get quicker result sets, instead of going for sel * from table , if you want to check the columns and their names, for one instance. Fetch time will be minimized.

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