Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Chapter 15, Problem 8PE
Explanation of Solution
Sort-based
Suppose be two relations and has to be computed.
- Sort relation “s” on “S” for sort-based algorithm. Sort relation “r” on (T, S).
- Now, start scanning “r” and look at the “T” attribute values of the first tuple.
- Scan “r” till tuples have same value of “T”. Also scan “s” simultaneously and check whether every tuple of “s” also occurs as the “S” attribute of “r”, in a fashion similar to merge join.
- If this is the case, output that value of “T” and proceed with the next value of “T”.
- Relation “s” may have to be scanned multiple times but “r” will only be scanned once.
- Total disk accesses, after sorting both the relations, will be “|r| 9 N * |s|”, where “N” is the number of distinct values of “T” in “r”.
Hash-based algorithm for computing the relational division operation:
- Let assume that for any value of “T”, all tuples in “r” with that “T” value fit in memory, and consider the general case at the end...
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Consider the following scenario in which host 10.0.0.1 is communicating with an external SMTP mail server at IP
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Just wanted to know, if you had a scene graph, how do you get multiple components from a specific scene node within a scene graph? Like if I wanted to get a component from wheel from the scene graph, does that require traversing still?
Like if a physics component requires a transform component and these two component are part of the same scene node. How does the physics component knows how to get the scene object's transform it is attached to, this being in a scene graph?
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