Distributed Queries

Question 1

How does Symmetric Repartitioning work?

Answer 1

1. shuffle both tables on Join-key
2. equality-based join on nodes

Question 2

How does asymmetric partitioning work?

Answer 2

• one table is partitioned on join key
• shuffle only the other table on the same key

Question 3

How does Fragment-and-Replicate work?

Answer 3

• replicate smaller table to all nodes
• join on all nodes

Question 4

Semi-reduction Join Idea

Answer 4

• compute projection of join keys on foreign table
• ship projection to other node
• execute semi-join only for relevant tuples
• send back result