Partial details of an execution plan. Which statement correctly describes the BITMAP AND operation?

The correct answer is D. It produces a bitmap, representing fact table rows that join with qualified dimension table rows from all. Additional set operations will be done for the customer dimension and the product dimension. At this point in the star query processing, there are three bitmaps. Each bitmap corresponds to a separate dimension table, and each bitmap represents the set of rows of the fact table…

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Question

Exhibit

Options

AIt produces a bitmap, representing dimension table rows from all dimension tables that join with qualified
BIt produces a concentration of the bitmaps for all dimension tables.
CIt produces a bitmap, representing fact table rows that do not join with qualified dimension table rows from
DIt produces a bitmap, representing fact table rows that join with qualified dimension table rows from all

How the community answered

(46 responses)

A
11% (5)
B
7% (3)
C
2% (1)
D
80% (37)

Explanation

Additional set operations will be done for the customer dimension and the product dimension. At this point in the star query processing, there are three bitmaps. Each bitmap corresponds to a separate dimension table, and each bitmap represents the set of rows of the fact table that satisfy that individual dimension's constraints. These three bitmaps are combined into a single bitmap using the bitmap AND operation. This final bitmap represents the set of rows in the fact table that satisfy all of the constraints on the dimension table.

Topics

#BITMAP AND#bitmap indexes#star schema#fact table

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