ReQL command: inner_join

Command syntax

sequence.inner_join(other_sequence, predicate_function) → stream
array.inner_join(other_sequence, predicate_function) → array

Description

Returns an inner join of two sequences.

The returned sequence represents an intersection of the left-hand sequence and the right-hand sequence: each row of the left-hand sequence will be compared with each row of the right-hand sequence to find all pairs of rows which satisfy the predicate. Each matched pair of rows of both sequences are combined into a result row. In most cases, you will want to follow the join with zip to combine the left and right results.

Note that inner_join is slower and much less efficient than using eq_join or concat_map with get_all. You should avoid using inner_join in commands when possible.

Example: Return a list of all matchups between Marvel and DC heroes in which the DC hero could beat the Marvel hero in a fight.

r.table('marvel').inner_join(r.table('dc')) {|marvel_row, dc_row|
    marvel_row[:strength] < dc_row[:strength]
}.zip().run(conn)

(Compare this to an outer_join with the same inputs and predicate, which would return a list of all Marvel heroes along with any DC heroes with a higher strength.)