Collection Methods

This is a translation reference to convert the Oracle Collection Methods to Snowflake

This section is a work in progress, information may change in the future

Some parts in the output code are omitted for clarity reasons.

Description

A collection method is a PL/SQL subprogram—either a function that returns information about a collection or a procedure that operates on a collection. Collection methods make collections easier to use and your applications easier to maintain.

(Oracle PL/SQL Language Reference COLLECTION METHODS)

Some of these methods can be mapped to native Snowflake semi-structured operations. The ones that can't or have differences will be mapped to a UDF implementation.

Current SnowConvert Support

The next table shows a summary of the current support provided by the SnowConvert tool. Please keep into account that translations may still not be final, and more work may be needed.

Sample Source Patterns

COUNT

This method returns the count of "non-undefined" (not to be confused with null) elements within a collection (nested tables can become sparse leaving these elements in between). In associative arrays, it returns the number of keys in the array.

Oracle

Query

CREATE OR REPLACE PROCEDURE collection_count
IS
    TYPE varray_typ IS VARRAY(5) OF INTEGER;
    TYPE nt_typ IS TABLE OF INTEGER;
    TYPE aa_typ IS TABLE OF INTEGER INDEX BY VARCHAR2(20);
    
    associative_array aa_typ := aa_typ('abc'=>1, 'bca'=>1);
    varray_variable varray_typ := varray_typ(1, 2, 3);
    nt_variable nt_typ := nt_typ(1, 2, 3, 4);
BEGIN
    DBMS_OUTPUT.PUT_LINE(associative_array.COUNT);
    DBMS_OUTPUT.PUT_LINE(varray_variable.COUNT);
    DBMS_OUTPUT.PUT_LINE(nt_variable.COUNT);
END;

CALL collection_count();

Result

DBMS OUTPUT
-----------
2
3
4

Snowflake

The snowflake equivalent is the ARRAY_SIZE method.

Query

CREATE OR REPLACE PROCEDURE PUBLIC.collection_count()
RETURNS VARCHAR
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
DECLARE
    associative_array OBJECT := OBJECT_CONSTRUCT('abc', 1, 'bca', 1);
    varray_variable ARRAY := ARRAY_CONSTRUCT(1, 2, 3);
    nt_variable ARRAY := ARRAY_CONSTRUCT(1, 2, 3, 4);
BEGIN
    CALL DBMS_OUTPUT.PUT_LINE(ARRAY_SIZE(OBJECT_KEYS(:associative_array)));
    CALL DBMS_OUTPUT.PUT_LINE(ARRAY_SIZE(:varray_variable));
    CALL DBMS_OUTPUT.PUT_LINE(ARRAY_SIZE(:nt_variable));
END;
$$;

CALL PUBLIC.collection_count();
SELECT * FROM DBMS_OUTPUT.DBMS_OUTPUT_LOG;

Result

DBMS OUTPUT
-----------
2
3
4

EXISTS

This method returns true if the given element is contained within the collection. In associative arrays, it tests if the key is contained.

Oracle

Query

CREATE OR REPLACE PROCEDURE collection_exists
IS
    TYPE nt_typ IS TABLE OF INTEGER;
    TYPE aa_typ IS TABLE OF INTEGER INDEX BY VARCHAR2(20);
    
    associative_array aa_typ := aa_typ('abc'=>1, 'bca'=>1);
    nt_variable nt_typ := nt_typ(1, 2, 3, 4);
BEGIN
    IF associative_array.EXISTS('abc')
    THEN DBMS_OUTPUT.PUT_LINE('Found');
    END IF;
    
    IF NOT associative_array.EXISTS('not found')
    THEN DBMS_OUTPUT.PUT_LINE('Not found');
    END IF;
    
    IF nt_variable.EXISTS(1)
    THEN DBMS_OUTPUT.PUT_LINE('Found');
    END IF;
    
    IF NOT nt_variable.EXISTS(5)
    THEN DBMS_OUTPUT.PUT_LINE('Not found');
    END IF;
END;
/

CALL collection_exists();

Result

DBMS OUTPUT
-----------
2