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Imagine that the SELECT statement that defines the view selects 10 million rows, and when you select from the view you want only 10,000 of these.
Selecting from the view means that the first, large, SELECT has to occur to materialize the view, and only then can your second, small, SELECT proceed.
If you had selected the 10,000 rows from the base table, only the small SELECT would need to be executed.
Selecting from the view means that the first, large, SELECT has to occur to materialize the view, and only then can your second, small, SELECT proceed.
If you had selected the 10,000 rows from the base table, only the small SELECT would need to be executed.
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Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
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