join — combine data from two inputs using a join predicate
( => left path => right path )
| [anti|inner|left|right] join on <left-key>=<right-key> [<field>:=<right-expr>, ...]
join operator combines records from two inputs based on whether
<left-key> expression (evaluated in the context of the left input)
is equal to the
<right-key> expression (evaluated in the context of
the right input) omitting values where there is no match (or including them
in the case of anti join).
The available join types are:
- inner - output only values that match
- left - output all left values with merged components from
- right - output as a left join but with the roles of the inputs and
- anti - output left values whose left key does not have a matching right key
For anti join, the
<right-expr> is undefined and thus cannot be specified.
Currently, only exact equi-join is supported and the inputs must be sorted in ascending order by their respective keys. Also, the join keys must be field expressions. A future version of join will not require sorted inputs and will have more flexible join expressions.
The join tutorial includes several examples.