Re: When are projections done?

From: The Boss <usenet_at_No.Spam.Please.invalid>
Date: Tue, 2 Mar 2010 22:24:02 +0100
Message-ID: <4b8d81f4$0$22390$>

jbdhl wrote:
> Consider a table and a query referring to only a subset of the columns
> in that table. How early in the query evaluation is the projection
> carried out?
> Are the columns to be selected filtered out as early as in the very
> access method that reads the table rows from the buffer, or are the
> projection handled later, after the whole row has been fetched by the
> access method?
> Does it depend on the complexity of the query, how far down the three
> that the projection is handled out?
> Thanks!

What problem are you trying to solve, given the fact that you've been asking this very same question in groups/forums for 3 different DBMS's: (MSSQL-forum)

Received on Tue Mar 02 2010 - 15:24:02 CST

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