Apache Spark GraphX and Graph Processing 2

Question 1

What computation model does the Pregel API in GraphX implement?

Accepted Answer

Bulk-synchronous message-passing between vertices

Answer

MapReduce-based batch aggregation

Answer

Streaming micro-batch graph updates

Answer

SQL-style declarative graph traversal

Question 2

In GraphX's `aggregateMessages`, what is the role of the `sendMsg` function?

Accepted Answer

To define what messages are sent along each edge to neighboring vertices

Answer

To send final computation results back to the driver

Answer

To broadcast vertex attributes to all partitions

Answer

To serialize edge data for network transfer

Question 3

What does GraphX's `connectedComponents()` algorithm store as each vertex's attribute in the result graph?

Accepted Answer

The lowest VertexId in its connected component

Answer

A list of all neighbor IDs in its component

Answer

The number of vertices in its component

Answer

A Boolean flag indicating if the vertex is a component root

Question 4

What does the `mapVertices` operation in GraphX do?

Accepted Answer

Transforms vertex attributes using a user-defined function without changing graph structure

Answer

Moves vertices to different partitions for load balancing

Answer

Remaps vertex IDs to new sequential integer values

Answer

Creates a sorted copy of the graph ordered by vertex attribute

Question 5

What is the purpose of the `subgraph` operation in GraphX?

Accepted Answer

To extract a subset of vertices and edges that satisfy a given predicate

Answer

To split a graph into two equal halves for parallel processing

Answer

To create a coarser hierarchical summary of the graph

Answer

To merge two separate graphs into one larger graph

Question 6

Which GraphX algorithm ranks vertices based on the number and quality of their incoming edges?

Accepted Answer

PageRank

Answer

Triangle Count

Answer

Shortest Paths

Answer

Label Propagation

Question 7

What does calling `Graph.reverse` on a GraphX graph produce?

Accepted Answer

A new graph with all edge directions flipped while keeping vertex and edge attributes unchanged

Answer

A graph with vertices listed in reverse order

Answer

A graph with edges sorted from destination to source alphabetically

Answer

A backup replica of the graph on a secondary cluster