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Posted by Dan Guzman on 10/04/06 11:58
> My assumption is that, entire page (8K) containg the rows with all the
> colunmns are transferred to the memory and from the memory the select
> columns are displayed .
Correct. Keep in mind that non-clustered index pages can also be used and
are typically more dense than data pages. A composite index on column1 and
column2 will cover your query so the optimizer will probably choose to scan
that index rather than the entire table.
--
Hope this helps.
Dan Guzman
SQL Server MVP
<masri999@gmail.com> wrote in message
news:1159952825.340114.188580@m7g2000cwm.googlegroups.com...
> Hello,
>
> I need a clarification on the mechanism of sql server fetches records
> to memory (buffer)
>
> Example: A Table ( Table1 ) having 10 Columns
> (column1,column2,column3,column4 etc)
>
> When SELECT column1,column2 FROM Table1 is executed
>
> Whether all columns are trasnferred to the server memory from the disk
>
> OR only column1 and column2 are read from disk to memory .
>
> My assumption is that, entire page (8K) containg the rows with all the
> colunmns are transferred to the memory and from the memory the select
> columns are displayed .
>
> Please confirm
>
> Thanks
>
> M A Srinivas
>
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