XML Exam I10-003 Topic 5 Question 42 Discussion

Consider the execution of [XQuery] as referenced in a separate window.

Assume that the following index is used when executing this [XQuery] on a certain XMLDB.

[Index Usage Standards] (assumed)

Use only the most efficient index when an index for both $A/@type and $B/@type is created.

If only one index is created, use that index.

Do not use an index if none is created.

Assume the following circumstances regarding the statistical values related to the execution of this [XQuery].

[Statistical Value] (assumed)

When creating an index for $A/@type, the response time when updating $A/@type data is one millisecond longeron average.

When creating an index for $B/@type. the response time when updating $B/@type data is one millisecond longeron average.

When creating an index for either $A/@type or$B/@type, or when creating an index for both, the response time of [XQuery] execution is at least two milliseconds shorter on average.

Of all of the values of $A/@type, the rate of inclusion of identical values is 1% on average. Of all of the values of $B/@type, the rate of inclusion of identical values is 2% on average. The ratio of $A/@type data update, $B/@type data update, and [XQuery] execution is 1:1:1 on average.

When the number of data items for both $A/@type and $B/@type are extremely large and almost identical, which is the most effective method for improving overall execution efficiency? Assume that this XMLDB has no other automated optimization functions than those described above. Assume that no other queries are executed.