Adding TMC canalespy query helpers

parsons/databases/table.py

@@ -1,4 +1,5 @@
 import logging
+import datetime
 
 logger = logging.getLogger(__name__)
 
@@ -164,3 +165,69 @@ def truncate(self):
 
         self.db.query(f"TRUNCATE TABLE {self.table}")
         logger.info(f"{self.table} truncated.")
+
+    def dedup_table(
+        self,
+        order_by_column_name=None,
+        order_by_direction=None,
+        cascade=False,
+        columns_to_ignore=None,
+    ):
+        """
+        Description:
+            This function re-creates a deduped version of a table by grabbing
+            all columns and inserting those into a partition statement for
+            row_number().
+        Args:
+            order_by_column_name: str (optional)
+                Column name of specific column that you would like to dedup using order by
+            order_by_direction: str (optional)
+                Order by direction, if you would like to dedup by ordering by a specific column,
+                this is the direction of the order by
+                example: 'asc'
+            cascade: bool (optional)
+                Set to True if you want any dependent views to be dropped -
+                queries will fail if there are dependent views and this is set to False.
+           columns_to_ignore: list (optional)
+                List any columns that should be ignored in the dedup
+        """
+        current_timestamp = datetime.datetime.now().strftime("%Y%m%d%H%M%S")
+        run_cascade = "CASCADE" if cascade else ""
+        order_by_column_name = (
+            "random()" if order_by_column_name is None else order_by_column_name
+        )
+        if order_by_direction is None and order_by_column_name is not None:
+            raise Exception("order_by_direction argument is blank")
+
+        columns_list = self.columns
+
+        # remove order_by columns
+        columns_list.remove(
+            order_by_column_name
+        ) if order_by_column_name is not None else None
+
+        # remove ignore columns
+        if columns_to_ignore is not None:
+            for column in columns_to_ignore:
+                columns_list.remove(column)
+
+        partition = ", ".join(columns_list)
+
+        dedup_query = f"""
+            create table {self.table}_temp_{current_timestamp} as
+            (select *
+            , row_number() over (partition by {partition}
+            order by {order_by_column_name} {order_by_direction}) as dup
+            from {self.table})
+            where dup=1;
+            alter table {self.table}_temp_{current_timestamp}
+            drop column dup;
+            truncate table {self.table}
+            insert into {self.table} (select * from {self.table}_temp_{current_timestamp})
+             {run_cascade};
+        """
+
+        self.db.query(dedup_query)
+        logger.info(f"Finished deduping {self.table}...")
+
+        return None

test/test_databases/test_mysql.py

@@ -104,6 +104,11 @@ def test_truncate(self):
         self.tbl.truncate()
         self.assertEqual(self.tbl.num_rows, 0)
 
+    def test_dedup_table(self):
+
+        self.tbl.dedup_table(order_by_column_name="user_name")
+        self.assertEqual(self.tbl.num_rows, 2)
+
     def test_get_rows(self):
 
         data = [