Question

True or False for mysql and mongodb:

1. Building a B-tree on one of a tables attributes will improve the query time for all queries.

2. B-trees have a branching factor of 2 or 4.

3. B-tree insertion algorithms move data to a sibling node if the node inserted into is full.

4. Mongo provides everything relational databases do, but insertions are much slower.

5. If one maps from a well-designed ER diagram to the relational model, the database may or may not be in BCNF, but it will likely be “pretty good.”

Answer 1

Answer:

1. Building a B-tree on one of a tables attributes will improve the query time for all queries. - True

2. B-trees have a branching factor of 2 or 4. - False

B-trees are often called 2-3-4 trees because their branching factor is always 2, 3, or 4. To guarantee a branching factor of 2 to 4, each internal node must store 1 to 3 keys.

3. B-tree insertion algorithms move data to a sibling node if the node inserted into is full. - True

Insert the new key at the proper location, but if the node has a maximum number of keys already:

• The node, along with a newly inserted key, will split from the middle element.
• The middle element will become the parent for the other two child nodes.
• The nodes must re-arrange keys in ascending order.

4. Mongo provides everything relational databases do, but insertions are much slower. - False

5. If one maps from a well-designed ER diagram to the relational model, the database may or may not be in BCNF, but it will likely be “pretty good.” - True

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