Translation reference for User-defined function (UDF) Call
Some parts in the output code are omitted for clarity reasons.
Description
As is widely acknowledged, non-scalar user-defined functions (UDFs) in Oracle are converted into Snowflake stored procedures to accommodate more intricate functionalities.
This transformation also alters the way the function is invoked, transitioning from a traditional function call to a stored procedure call.
For additional details regarding the invocation of stored procedures, refer to the documentation accessible here: PROCEDURE CALL.
Sample Source Patterns
Consider the next function and tables for the examples below.
IN -> Oracle_01.sql
CREATE OR REPLACEFUNCTIONsum_to_varchar_function(p_number1 INNUMBER, p_number2 INNUMBER)RETURNVARCHARIS result VARCHAR(100);BEGIN result := TO_CHAR(p_number1 + p_number2);RETURN result;END sum_to_varchar_function;CREATETABLEexample_table ( id NUMBER, column1 NUMBER);INSERT INTO example_table VALUES (1, 15);CREATETABLEresult_table ( id NUMBER, result_col VARCHAR(100));
OUT -> Oracle_01.sql
CREATE OR REPLACEFUNCTIONsum_to_varchar_function (p_number1 NUMBER(38, 18), p_number2 NUMBER(38, 18))RETURNSVARCHARLANGUAGESQLCOMMENT ='{ "origin": "sf_sc", "name": "snowconvert", "version": { "major": 0, "minor": 0, "patch": "0" }, "attributes": { "component": "oracle", "convertedOn": "11/14/2024", "domain": "test" }}'AS$$WITH declaration_variables_cte1 AS (SELECT TO_CHAR(p_number1 + p_number2) AS result )SELECT resultFROM declaration_variables_cte1$$;CREATE OR REPLACETABLEexample_table ( id NUMBER(38, 18) /*** SSC-FDM-0006 - NUMBER TYPE COLUMN MAY NOT BEHAVE SIMILARLY IN SNOWFLAKE. ***/, column1 NUMBER(38, 18) /*** SSC-FDM-0006 - NUMBER TYPE COLUMN MAY NOT BEHAVE SIMILARLY IN SNOWFLAKE. ***/ )COMMENT ='{ "origin": "sf_sc", "name": "snowconvert", "version": { "major": 0, "minor": 0, "patch": "0" }, "attributes": { "component": "oracle", "convertedOn": "11/14/2024", "domain": "test" }}';INSERT INTO example_tableVALUES (1, 15);CREATE OR REPLACETABLEresult_table ( id NUMBER(38, 18) /*** SSC-FDM-0006 - NUMBER TYPE COLUMN MAY NOT BEHAVE SIMILARLY IN SNOWFLAKE. ***/, result_col VARCHAR(100) )COMMENT ='{ "origin": "sf_sc", "name": "snowconvert", "version": { "major": 0, "minor": 0, "patch": "0" }, "attributes": { "component": "oracle", "convertedOn": "11/14/2024", "domain": "test" }}';
When a function call is embedded within a query, the invocation process becomes more intricate due to Snowflake's limitation of not being able to call procedures directly within queries. To overcome this limitation, the procedure invocation is moved outside the query, and the result is assigned to a variable. This variable is then referenced within the query, thereby achieving functional equivalence. This approach allows for the execution of more complex behaviors within Snowflake queries while adhering to the procedural constraints.
Oracle
IN -> Oracle_03.sql
CREATEORREPLACEPROCEDURE procedure_calling_function(param1 INNUMBER)IS result_value VARCHAR(200); result_value2 VARCHAR(200);BEGINSELECT sum_to_varchar_function(1, param1) AS result_column, sum_to_varchar_function(2, param1) AS result_column2INTO result_value, result_value2FROM example_table ext;INSERT INTO result_table VALUES (1, result_value);INSERT INTO result_table VALUES (2, result_value2);END;BEGIN procedure_calling_function(5);END;
1. Unsupported Usage of UDFs in Queries with Query Dependencies
When calling User-Defined Functions (UDFs) within queries with query dependencies, scenarios involving embedded functions with columns as arguments are not supported. This limitation arises because the column values cannot be accessed from outside the query. Examples of unsupported scenarios include:
BEGINSELECT sum_to_varchar_function(ext.col1, ext.col2) -- columns as arguments not supportedINTO result_valueFROM example_table ext;END;
The supported scenarios include function calls with other types of arguments such as literal values, external variables, or parameters. For instance: