Use INSERT ON CONFLICT for --overwrite option (#91)
Use INSERT ON CONFLICT for --overwrite option (#91)

Co-authored-by: Pyry Liukas <724218864d869a05ca0c7c18a443db2c580d3b6d@taiste.fi>
Co-authored-by: Mikko Harju <6c2e114534db2df470ab0be06609e9cc3d75b09b@taiste.fi>
ankane/pgsync