Returning tabular data from a Python stored procedureÂļ

You can write a procedure that returns data in tabular form. To write a procedure that returns tabular data, do the following:

  • Specify TABLE(...) as the procedure’s return type in your CREATE PROCEDURE statement.

    As TABLE parameters, you can specify the returned data’s column names and types if you know them. If you don’t know the returned columns when defining the procedure — such as when they’re specified at run time — you can leave out the TABLE parameters. When you do, the procedure’s return value columns will be converted from the columns in the DataFrame returned by its handler. Column data types will be converted to SQL according to the mapping specified in SQL-Python Data Type Mappings.

  • Write the handler so that it returns the tabular result in a Snowpark DataFrame.

    For more information about dataframes, see Working with DataFrames in Snowpark Python.

ExamplesÂļ

The examples in this section illustrate returning tabular values from a procedure that filters for rows where a column matches a string.

Defining the dataÂļ

Code in the following example creates a table of employees.

CREATE OR REPLACE TABLE employees(id NUMBER, name VARCHAR, role VARCHAR);
INSERT INTO employees (id, name, role) VALUES (1, 'Alice', 'op'), (2, 'Bob', 'dev'), (3, 'Cindy', 'dev');
Copy

Specifying return column names and typesÂļ

This example specifies column names and types in the RETURNS TABLE() statement.

CREATE OR REPLACE PROCEDURE filterByRole(tableName VARCHAR, role VARCHAR)
RETURNS TABLE(id NUMBER, name VARCHAR, role VARCHAR)
LANGUAGE PYTHON
RUNTIME_VERSION = '3.9'
PACKAGES = ('snowflake-snowpark-python')
HANDLER = 'filter_by_role'
AS
$$
from snowflake.snowpark.functions import col

def filter_by_role(session, table_name, role):
   df = session.table(table_name)
   return df.filter(col("role") == role)
$$;
Copy

Omitting return column names and typesÂļ

Code in the following example declares a procedure that allows return value column names and types to be extrapolated from columns in the handler’s return value. It omits the column names and types from the RETURNS TABLE() statement.

CREATE OR REPLACE PROCEDURE filterByRole(tableName VARCHAR, role VARCHAR)
RETURNS TABLE()
LANGUAGE PYTHON
RUNTIME_VERSION = '3.9'
PACKAGES = ('snowflake-snowpark-python')
HANDLER = 'filter_by_role'
AS
$$
from snowflake.snowpark.functions import col

def filter_by_role(session, table_name, role):
  df = session.table(table_name)
  return df.filter(col("role") == role)
$$;
Copy

Calling the procedureÂļ

The following example calls the stored procedure:

CALL filterByRole('employees', 'dev');
Copy

The procedure call produces the following output:

+----+-------+------+
| ID | NAME  | ROLE |
+----+-------+------+
| 2  | Bob   | dev  |
| 3  | Cindy | dev  |
+----+-------+------+
Language: English