A LEFT SEMIJOIN (or just SEMIJOIN ) gives only those rows in the left rowset that have a matching row in the right rowset. The RIGHT SEMIJOIN gives only those rows in the right rowset that have a matching row in the left rowset. The join expression in the ON clause specifies how to determine the match.

How does left semi join work?

If there are multiple matching rows in the right-hand column, an INNER JOIN will return one row for each match on the right table, while a LEFT SEMI JOIN only returns the rows from the left table, regardless of the number of matching rows on the right side. … Then a LEFT SEMI JOIN is the appropriate query to use.

What is left semi join PySpark?

PySpark leftsemi join is similar to inner join difference being left semi-join returns all columns from the left DataFrame/Dataset and ignores all columns from the right dataset.