Add postgres upsert

awswrangler/_databases.py

@@ -256,3 +256,9 @@ def convert_value_to_native_python_type(value: Any) -> Any:
         chunk_placeholders = ", ".join([f"({column_placeholders})" for _ in range(len(parameters_chunk))])
         flattened_chunk = [convert_value_to_native_python_type(value) for row in parameters_chunk for value in row]
         yield chunk_placeholders, flattened_chunk
+
+
+def validate_mode(mode: str, allowed_modes: List[str]) -> None:
+    """Check if mode is included in allowed_modes."""
+    if mode not in allowed_modes:
+        raise exceptions.InvalidArgumentValue(f"mode must be one of {', '.join(allowed_modes)}")

awswrangler/_utils.py

@@ -227,7 +227,7 @@ def chunkify(lst: List[Any], num_chunks: int = 1, max_length: Optional[int] = No
     if not lst:
         return []
     n: int = num_chunks if max_length is None else int(math.ceil((float(len(lst)) / float(max_length))))
-    np_chunks = np.array_split(lst, n)  # type: ignore
+    np_chunks = np.array_split(lst, n)
     return [arr.tolist() for arr in np_chunks if len(arr) > 0]
 
 

awswrangler/mysql.py

@@ -292,8 +292,8 @@ def to_sql(
         Schema name
     mode : str
         Append, overwrite, upsert_duplicate_key, upsert_replace_into, upsert_distinct.
-            append: Inserts new records into table
-            overwrite: Drops table and recreates
+            append: Inserts new records into table.
+            overwrite: Drops table and recreates.
             upsert_duplicate_key: Performs an upsert using `ON DUPLICATE KEY` clause. Requires table schema to have
             defined keys, otherwise duplicate records will be inserted.
             upsert_replace_into: Performs upsert using `REPLACE INTO` clause. Less efficient and still requires the
@@ -340,17 +340,16 @@ def to_sql(
     """
     if df.empty is True:
         raise exceptions.EmptyDataFrame()
+
     mode = mode.strip().lower()
-    modes = [
+    allowed_modes = [
         "append",
         "overwrite",
         "upsert_replace_into",
         "upsert_duplicate_key",
         "upsert_distinct",
     ]
-    if mode not in modes:
-        raise exceptions.InvalidArgumentValue(f"mode must be one of {', '.join(modes)}")
-
+    _db_utils.validate_mode(mode=mode, allowed_modes=allowed_modes)
     _validate_connection(con=con)
     try:
         with con.cursor() as cursor:

awswrangler/postgresql.py

@@ -277,6 +277,7 @@ def to_sql(
     varchar_lengths: Optional[Dict[str, int]] = None,
     use_column_names: bool = False,
     chunksize: int = 200,
+    upsert_conflict_columns: Optional[List[str]] = None,
 ) -> None:
     """Write records stored in a DataFrame into PostgreSQL.
 
@@ -291,7 +292,11 @@ def to_sql(
     schema : str
         Schema name
     mode : str
-        Append or overwrite.
+        Append, overwrite or upsert.
+            append: Inserts new records into table.
+            overwrite: Drops table and recreates.
+            upsert: Perform an upsert which checks for conflicts on columns given by `upsert_conflict_columns` and
+            sets the new values on conflicts. Note that `upsert_conflict_columns` is required for this mode.
     index : bool
         True to store the DataFrame index as a column in the table,
         otherwise False to ignore it.
@@ -307,6 +312,9 @@ def to_sql(
         inserted into the database columns `col1` and `col3`.
     chunksize: int
         Number of rows which are inserted with each SQL query. Defaults to inserting 200 rows per query.
+    upsert_conflict_columns: List[str], optional
+        This parameter is only supported if `mode` is set top `upsert`. In this case conflicts for the given columns are
+        checked for evaluating the upsert.
 
     Returns
     -------
@@ -330,6 +338,12 @@ def to_sql(
     """
     if df.empty is True:
         raise exceptions.EmptyDataFrame()
+
+    mode = mode.strip().lower()
+    allowed_modes = ["append", "overwrite", "upsert"]
+    _db_utils.validate_mode(mode=mode, allowed_modes=allowed_modes)
+    if mode == "upsert" and not upsert_conflict_columns:
+        raise exceptions.InvalidArgumentValue("<upsert_conflict_columns> needs to be set when using upsert mode.")
     _validate_connection(con=con)
     try:
         with con.cursor() as cursor:
@@ -347,13 +361,18 @@ def to_sql(
                 df.reset_index(level=df.index.names, inplace=True)
             column_placeholders: str = ", ".join(["%s"] * len(df.columns))
             insertion_columns = ""
+            upsert_str = ""
             if use_column_names:
                 insertion_columns = f"({', '.join(df.columns)})"
+            if mode == "upsert":
+                upsert_columns = ", ".join(df.columns.map(lambda column: f"{column}=EXCLUDED.{column}"))
+                conflict_columns = ", ".join(upsert_conflict_columns)  # type: ignore
+                upsert_str = f" ON CONFLICT ({conflict_columns}) DO UPDATE SET {upsert_columns}"
             placeholder_parameter_pair_generator = _db_utils.generate_placeholder_parameter_pairs(
                 df=df, column_placeholders=column_placeholders, chunksize=chunksize
             )
             for placeholders, parameters in placeholder_parameter_pair_generator:
-                sql: str = f'INSERT INTO "{schema}"."{table}" {insertion_columns} VALUES {placeholders}'
+                sql: str = f'INSERT INTO "{schema}"."{table}" {insertion_columns} VALUES {placeholders}{upsert_str}'
                 _logger.debug("sql: %s", sql)
                 cursor.executemany(sql, (parameters,))
             con.commit()

tests/test_postgresql.py

@@ -219,3 +219,155 @@ def test_dfs_are_equal_for_different_chunksizes(postgresql_table, postgresql_con
     df["c1"] = df["c1"].astype("string")
 
     assert df.equals(df2)
+
+
+def test_upsert(postgresql_table, postgresql_con):
+    create_table_sql = (
+        f"CREATE TABLE public.{postgresql_table} "
+        "(c0 varchar NULL PRIMARY KEY,"
+        "c1 int NULL DEFAULT 42,"
+        "c2 int NOT NULL);"
+    )
+    with postgresql_con.cursor() as cursor:
+        cursor.execute(create_table_sql)
+        postgresql_con.commit()
+
+    df = pd.DataFrame({"c0": ["foo", "bar"], "c2": [1, 2]})
+
+    with pytest.raises(wr.exceptions.InvalidArgumentValue):
+        wr.postgresql.to_sql(
+            df=df,
+            con=postgresql_con,
+            schema="public",
+            table=postgresql_table,
+            mode="upsert",
+            upsert_conflict_columns=None,
+            use_column_names=True,
+        )
+
+    wr.postgresql.to_sql(
+        df=df,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=["c0"],
+        use_column_names=True,
+    )
+    wr.postgresql.to_sql(
+        df=df,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=["c0"],
+        use_column_names=True,
+    )
+    df2 = wr.postgresql.read_sql_table(con=postgresql_con, schema="public", table=postgresql_table)
+    assert bool(len(df2) == 2)
+
+    wr.postgresql.to_sql(
+        df=df,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=["c0"],
+        use_column_names=True,
+    )
+    df3 = pd.DataFrame({"c0": ["baz", "bar"], "c2": [3, 2]})
+    wr.postgresql.to_sql(
+        df=df3,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=["c0"],
+        use_column_names=True,
+    )
+    df4 = wr.postgresql.read_sql_table(con=postgresql_con, schema="public", table=postgresql_table)
+    assert bool(len(df4) == 3)
+
+    df5 = pd.DataFrame({"c0": ["foo", "bar"], "c2": [4, 5]})
+    wr.postgresql.to_sql(
+        df=df5,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=["c0"],
+        use_column_names=True,
+    )
+
+    df6 = wr.postgresql.read_sql_table(con=postgresql_con, schema="public", table=postgresql_table)
+    assert bool(len(df6) == 3)
+    assert bool(len(df6.loc[(df6["c0"] == "foo") & (df6["c2"] == 4)]) == 1)
+    assert bool(len(df6.loc[(df6["c0"] == "bar") & (df6["c2"] == 5)]) == 1)
+
+
+def test_upsert_multiple_conflict_columns(postgresql_table, postgresql_con):
+    create_table_sql = (
+        f"CREATE TABLE public.{postgresql_table} "
+        "(c0 varchar NULL PRIMARY KEY,"
+        "c1 int NOT NULL,"
+        "c2 int NOT NULL,"
+        "UNIQUE (c1, c2));"
+    )
+    with postgresql_con.cursor() as cursor:
+        cursor.execute(create_table_sql)
+        postgresql_con.commit()
+
+    df = pd.DataFrame({"c0": ["foo", "bar"], "c1": [1, 2], "c2": [3, 4]})
+    upsert_conflict_columns = ["c1", "c2"]
+
+    wr.postgresql.to_sql(
+        df=df,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=upsert_conflict_columns,
+        use_column_names=True,
+    )
+    wr.postgresql.to_sql(
+        df=df,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=upsert_conflict_columns,
+        use_column_names=True,
+    )
+    df2 = wr.postgresql.read_sql_table(con=postgresql_con, schema="public", table=postgresql_table)
+    assert bool(len(df2) == 2)
+
+    df3 = pd.DataFrame({"c0": ["baz", "spam"], "c1": [1, 5], "c2": [3, 2]})
+    wr.postgresql.to_sql(
+        df=df3,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=upsert_conflict_columns,
+        use_column_names=True,
+    )
+    df4 = wr.postgresql.read_sql_table(con=postgresql_con, schema="public", table=postgresql_table)
+    assert bool(len(df4) == 3)
+
+    df5 = pd.DataFrame({"c0": ["egg", "spam"], "c1": [2, 5], "c2": [4, 2]})
+    wr.postgresql.to_sql(
+        df=df5,
+        con=postgresql_con,
+        schema="public",
+        table=postgresql_table,
+        mode="upsert",
+        upsert_conflict_columns=upsert_conflict_columns,
+        use_column_names=True,
+    )
+
+    df6 = wr.postgresql.read_sql_table(con=postgresql_con, schema="public", table=postgresql_table)
+    df7 = pd.DataFrame({"c0": ["baz", "egg", "spam"], "c1": [1, 2, 5], "c2": [3, 4, 2]})
+    df7["c0"] = df7["c0"].astype("string")
+    df7["c1"] = df7["c1"].astype("Int64")
+    df7["c2"] = df7["c2"].astype("Int64")
+    assert df6.equals(df7)