diff --git a/pandas/core/frame.py b/pandas/core/frame.py index a469f4965117b..74bd24901603d 100644 --- a/pandas/core/frame.py +++ b/pandas/core/frame.py @@ -10065,11 +10065,13 @@ def join( the order of the join key depends on the join type (how keyword). validate : str, optional If specified, checks if join is of specified type. + * "one_to_one" or "1:1": check if join keys are unique in both left - and right datasets. + and right datasets. * "one_to_many" or "1:m": check if join keys are unique in left dataset. * "many_to_one" or "m:1": check if join keys are unique in right dataset. * "many_to_many" or "m:m": allowed, but does not result in checks. + .. versionadded:: 1.5.0 Returns