Week 7 L1

Question 1

What do we mean by ad-hoc

Answer 1

When necessary or needed

Question 2

What are the downsides of relational relationships

Answer 2

need to define FK when using associative table
cannot add in ad-hoc way
recursive use of joins can be complex and slow

Question 3

What are the fundamentals of graph dbs ?

Answer 3

They are schemaless
Each node can have different properties like document DBS
A node can have a relationship with any other node
node pairs can have one or more relationship

Question 4

What are the key features of graph db relationships ?

Answer 4

Relationships have a type - any pair of nodes can have a relationship of any type
Relationships can have properties - relationships can be considered as nodes that join other nodes

Question 5

What do nodes represent

Answer 5

Nodes represent entities e.g. people in social networks, locations in distribution services

Question 6

What do edges represent

Answer 6

Edges represent relationships e.g. likes, plays, friends of , delivers to

Question 7

What do we mean by directional edges ?

Answer 7

Node to an edge is either incoming or outgoing for example A likes B does not mean B likes A

Question 8

What do properties do to a relationship

Answer 8

They add meaning

Question 9

What do nodes have ?

Answer 9

Lables and properties

Question 10

What do edges have ?

Answer 10

Types and properties

Question 11

What is relationship depth

Answer 11

Measured edges between one node and another

Question 12

What do we mean by graph traversal?

Answer 12

Means visiting nodes by following edges
Traversal starts with a chosen node.
Can follow incoming or outgoing nodes so travel in either direction

Question 13

What are the different types of traversal

Answer 13

Depth first traversal- Follows as far as possible along each edge to its end node then backtracks and follows the next unvisited edge and so on
Breadth first traversal
Follows the neighbouring nodes first then follows the next depth of neighbours and so on

Question 14

Why would you use indexes in graph databases ?

Answer 14

Speeds up search for specific nodes or edges.
Useful for finding the starting nodes for traversal.
Without index whole graph might be scanned.
Index for types of nodes etc

Question 15

How would you do a “who likes me “query?

Answer 15

Traverse the incoming nodes to me to depth 1 with edge type like

Question 16

What is the most popular graph database and what is its query language?

Answer 16

Neo4j has declarative query language called Cypher which is SQL like

Question 17

How to make relational DB as Graph

Answer 17

Separate all rows from their tables while keeping all relationships.