MSCEWI1068

User defined function was transformed to a Snowflake procedure.

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Severity

Low

Description

Snowflake user defined functions do not support the same features as Oracle or SQL Server. To maintain the functional equivalence the function is transformed to a Snowflake stored procedure. This will affect their usage in queries.

Example Code

1. Scalar Return Type

Input Code:

Oracle

CREATE OR REPLACE FUNCTION FUNC01(x NUMBER) RETURN NUMBER AS
  VAR1 NUMBER;
  BEGIN
   -- some pl sql statements
   RETURN VAR1;
  END FUNC01;

SQL Server

CREATE OR ALTER FUNCTION PURCHASING.FOO()
RETURNS INT
AS
BEGIN
    DECLARE @i int = 0, @p int;
    Select @p = COUNT(*) FROM PURCHASING.VENDOR
    
    WHILE (@p < 1000)
    BEGIN
        SET @i = @i + 1
        SET @p = @p + @i
    END
        
    IF (@i = 6)
        RETURN 1
    
    RETURN @p
END

Output Code:

From Oracle

/*** MSC-WARNING - MSCEWI1068 - USER DEFINED FUNCTION WAS TRANSFORMED TO SNOWFLAKE PROCEDURE ***/
CREATE OR REPLACE PROCEDURE PUBLIC.FUNC01(x FLOAT)
RETURNS FLOAT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
   /* mobilize helpers */
   /* pl sql statements translation */
   return VAR1;
$$;

From SQL Server

/*** MSC-WARNING - MSCEWI1068 - USER DEFINED FUNCTION WAS TRANSFORMED TO SNOWFLAKE PROCEDURE ***/
CREATE OR REPLACE PROCEDURE PURCHASING.FOO()
RETURNS STRING
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
   // REGION SnowConvert Helpers Code
      // some implementations here...
   // END REGION

   let I = 0;
   let P;
   SELECT(`COUNT(*) FROM PURCHASING.VENDOR`,[],(value) => P = value);
   while ( P < 1000 ) {
      I = I + 1;
      P = P + I;
   }
   if (I == 6) {
      return 1;
   }
   return P;
$$;

2. Table-Valued return type

Input code from SQL Server:

CREATE OR ALTER FUNCTION getGroupName
(@departmentId INT)
RETURNS @groupNames TABLE (groupName VARCHAR(15))
AS
BEGIN
DECLARE @name VARCHAR(30) = 'Another Department'  
WHILE @name = 'Another Department'   
BEGIN    
	IF (@departmentId < 3)
	BEGIN
		SET @name = 'engineering'
	END

	IF @departmentId = 3
	BEGIN
		SET @name = 'Tool Design'
	END

	SELECT @departmentId = @departmentId / 3
END
INSERT @groupNames SELECT @name

RETURN
END

Output code:

CREATE OR REPLACE PROCEDURE getGroupName(departmentId FLOAT) 
RETURNS VARIANT NOT NULL 
LANGUAGE JAVASCRIPT 
AS 
$$ 
    var sqlCommand = "CREATE OR REPLACE TEMPORARY TABLE groupNames (group_name VARCHAR(30));"; 
    var stmt = snowflake.createStatement( {sqlText: sqlCommand} ); 
    var resultSet = stmt.execute(); 
    resultSet.next(); 
    
    let name = 'Another department'
    while (name == 'Another department'){
      if (DEPARTMENTID < 3){
          name = 'engineering'
      }
      if (DEPARTMENTID == 3){
          name = 'Tool Design'
      }
      DEPARTMENTID = DEPARTMENTID / 3
    }
    
    sqlCommand = `INSERT INTO groupNames VALUES(:1);` 
    result = snowflake.execute(
        { 
        sqlText: sqlCommand, 
        binds: [name] 
        }
        );         
    
    var sqlCommand = "SELECT * FROM groupNames"; 
    var stmt = snowflake.createStatement( {sqlText: sqlCommand} ); 
    var resultSet = stmt.execute(); 
    resultSet.next(); 
    var arrayOfRows = [];
    arrayOfRows.push(resultSet.getColumnValue(1));
    
    return arrayOfRows;
$$; 

Recommendations

• Separate the queries to maintain the same logic as in the example below.

Input code from SQL Server:

CREATE OR ALTER FUNCTION getGroupName
(@departmentId INT)
RETURNS @groupNames TABLE (groupName VARCHAR(15))
AS
BEGIN
DECLARE @name VARCHAR(30) = 'Another Department'  
WHILE @name = 'Another Department'   
BEGIN    
	IF (@departmentId < 3)
	BEGIN
		SET @name = 'engineering'
	END
	  
	IF @departmentId = 3
	BEGIN
		SET @name = 'Tool Design'
	END
	
	SELECT @departmentId = @departmentId / 3
END
INSERT @groupNames SELECT @name
RETURN
END

SELECT * FROM getGroupName(9);

Output code:

CREATE OR REPLACE TEMPORARY TABLE groupNames (groupName VARCHAR(30));

CREATE OR REPLACE FUNCTION funcGetGroupName(departmentId FLOAT)
RETURNS VARCHAR
LANGUAGE JAVASCRIPT
AS 
$$
let name = 'Another department'
  while (name == 'Another department'){
      if (DEPARTMENTID < 3){
          name = 'engineering'
      }
      if (DEPARTMENTID == 3){
          name = 'Tool Design'
      }
      DEPARTMENTID = DEPARTMENTID / 3
   }
  return name
$$;

SET col = (SELECT funcGetGroupName(9));

INSERT INTO groupNames SELECT $col;

CREATE OR REPLACE FUNCTION getGroupName ()
RETURNS TABLE(groupName VARCHAR(30))
AS
$$   
    SELECT * FROM groupNames
$$;

SELECT * FROM TABLE(getGroupName ());

• The source code may need to be restructured to fit with the Snowflake user-defined functions approach.

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