diff --git a/pipeline/beam_etl/helpers/data_io.py b/pipeline/beam_etl/helpers/data_io.py
index 0f8c17e..482de3d 100644
--- a/pipeline/beam_etl/helpers/data_io.py
+++ b/pipeline/beam_etl/helpers/data_io.py
@@ -33,13 +33,16 @@ class ReadFromCsv(beam.DoFn):
 class WriteToPostgreSQL(beam.DoFn):
     """DoFn to write elements to a PostgreSQL database"""
 
-    def __init__(self, hostname, port, username, password, database, table):
+    def __init__(
+        self, hostname, port, username, password, database, table, table_key=None
+    ):
         self.hostname = hostname
         self.port = port
         self.username = username
         self.password = password
         self.database = database
         self.table = table
+        self.table_key = table_key
 
     def setup(self):
         self.connection = psycopg2.connect(
@@ -58,6 +61,19 @@ class WriteToPostgreSQL(beam.DoFn):
             INSERT INTO { self.table } ({ colnames })
             VALUES ({ values })
         """
+        if self.table_key is not None:
+            update_statement = ",".join(
+                f"{ col } = EXCLUDED.{ col }"
+                for col in element.keys()
+                if col != self.table_key
+            )
+            sql = (
+                sql
+                + f"""
+                ON CONFLICT ({ self.table_key }) DO UPDATE SET
+                    { update_statement }
+            """
+            )
         cursor.execute(sql, list(element.values()))
         self.connection.commit()
         cursor.close()
diff --git a/pipeline/beam_etl/main.py b/pipeline/beam_etl/main.py
index f9fcc16..ec85ed7 100644
--- a/pipeline/beam_etl/main.py
+++ b/pipeline/beam_etl/main.py
@@ -46,6 +46,7 @@ def main():
                 password=opts.pg_password,
                 database=opts.pg_database,
                 table=opts.pg_table,
+                table_key="gtin13",
             ))
         # fmt: on