diff --git a/etl/helpers/data_io.py b/etl/helpers/data_io.py
index e2dbfe9..2e51bc1 100644
--- a/etl/helpers/data_io.py
+++ b/etl/helpers/data_io.py
@@ -68,3 +68,30 @@ class WriteToPostgreSQL(beam.DoFn):
 
     def teardown(self):
         self.connection.close()
+
+
+class UpsertProductsToPg(WriteToPostgreSQL):
+    """DoFn to write products to PostgreSQL with our upsert logic"""
+
+    def execute_insert(self, row, cursor):
+        colnames = ",".join(row.keys())
+        values = ",".join(["%s"] * len(row))
+        sql = f"""
+           INSERT INTO { self.table } ({ colnames })
+           VALUES ({ values })
+           ON CONFLICT ({ self.table_key }) DO UPDATE
+           SET
+               gtin13 = EXCLUDED.gtin13,
+               primary_category = EXCLUDED.primary_category,
+               materials = EXCLUDED.materials,
+               packaging = EXCLUDED.packaging,
+               origin = EXCLUDED.origin,
+               weight = EXCLUDED.weight,
+           WHERE
+               primary_category != EXCLUDED.primary_category
+               materials != EXCLUDED.materials
+               packaging != EXCLUDED.packaging
+               origin != EXCLUDED.origin
+               weight != EXCLUDED.weight
+        """
+        cursor.execute(sql, list(row.values()))
diff --git a/etl/main.py b/etl/main.py
index 796c8fd..1ed229e 100644
--- a/etl/main.py
+++ b/etl/main.py
@@ -6,7 +6,7 @@ import apache_beam as beam
 
 from apache_beam.options.pipeline_options import PipelineOptions
 
-from helpers.data_io import ReadFromCsv, WriteToPostgreSQL
+from helpers.data_io import ReadFromCsv, UpsertProductsToPg
 from helpers.parse_row import parse_row
 
 
@@ -39,7 +39,7 @@ def main():
             | beam.Create([opts.input]) \
             | beam.ParDo(ReadFromCsv()) \
             | beam.Map(parse_row) \
-            | beam.ParDo(WriteToPostgreSQL(
+            | beam.ParDo(UpsertProductsToPg(
                 hostname=opts.pg_hostname,
                 port=opts.pg_port,
                 username=opts.pg_username,