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Select * vs Select column1, column2 ... performance !

AAGMay 16 2017 — edited May 17 2017

Hi ,

i have this very complex query joining mulitple tables.

When i do select * from <Query> , i am getting the results back in 2.5 seconds. Very good.

But when i select 10 column names from <query> it runs in 2.5 seconds for the first time but from 2nd time onwards it takes around 1 minute.

The explain plan looks similar for both the queries.

can somebody help me to guide where should i be looking at the issue ?

NOTE:- If i reduce no. of columns from 10 to 6 , the query results in less than a minute .. say around 50 seconds. The less the no. of columns in select clause, the time is getting reduced.

I selected only 1 column and it still resulted out in 30 seconds.

Thanks,

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Locked on Jun 14 2017
Added on May 16 2017
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