Module join 

Join operators: HashJoin, NestedLoopJoin, MergeJoin.

Structs

HashJoinNode

Hash join: builds a hash table from the build side, probes with the probe side.

MergeJoinNode

Merge join: requires both inputs sorted on join keys.

NestedLoopJoinNode

Nested loop join: for each outer row, scans all inner rows testing condition.