Collection Bulk Operations

This is a translation reference to convert the Oracle Collection Bulk Operations 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

The BULK COLLECT clause, a feature of bulk SQL, returns results from SQL to PL/SQL in batches rather than one at a time.

The BULK COLLECT clause can appear in:

  • SELECT INTO statement

  • FETCH statement

  • RETURNING INTO clause of:

    • DELETE statement

    • INSERT statement

    • UPDATE statement

    • EXECUTE IMMEDIATE statement

With the BULK COLLECT clause, each of the preceding statements retrieves an entire result set and stores it in one or more collection variables in a single operation (which is more efficient than using a loop statement to retrieve one result row at a time).

(Oracle PL/SQL Language Reference BULK COLLECT CLAUSE)

This section has some workarounds for SELECTs and FETCH Cursor with Bulk Clauses.

Sample Source Patterns

Source Table

Oracle

IN -> Oracle_01.sql
CREATE TABLE bulk_collect_table(col1 INTEGER);

INSERT INTO bulk_collect_table VALUES(1);
INSERT INTO bulk_collect_table VALUES(2);
INSERT INTO bulk_collect_table VALUES(3);
INSERT INTO bulk_collect_table VALUES(4);
INSERT INTO bulk_collect_table VALUES(5);
INSERT INTO bulk_collect_table VALUES(6);

Snowflake

OUT -> Oracle_01.sql
CREATE OR REPLACE TABLE bulk_collect_table (col1 INTEGER)
COMMENT = '{"origin":"sf_sc","name":"snowconvert","version":{"major":1, "minor":0},{"attributes":{"component":"oracle"}}'
;

INSERT INTO bulk_collect_table
VALUES(1);

INSERT INTO bulk_collect_table
VALUES(2);

INSERT INTO bulk_collect_table
VALUES(3);

INSERT INTO bulk_collect_table
VALUES(4);

INSERT INTO bulk_collect_table
VALUES(5);

INSERT INTO bulk_collect_table
VALUES(6);

Bulk Collect from a Table

Oracle

IN -> Oracle_02.sql
CREATE OR REPLACE PROCEDURE bulk_collect_procedure
IS
    CURSOR record_cursor IS
        SELECT *
        FROM bulk_collect_table;
        
    TYPE fetch_collection_typ IS TABLE OF record_cursor%ROWTYPE;
    fetch_collection_variable fetch_collection_typ;
    
    TYPE collection_typ IS TABLE OF bulk_collect_table%ROWTYPE;
    collection_variable collection_typ;
BEGIN
    SELECT * BULK COLLECT INTO collection_variable FROM bulk_collect_table;
    
    FOR i IN 1..collection_variable.COUNT
    LOOP
        DBMS_OUTPUT.PUT_LINE(collection_variable(i).col1);
    END LOOP;
    
    collection_variable := null;
    OPEN record_cursor;
    FETCH record_cursor BULK COLLECT INTO collection_variable;
    CLOSE record_cursor;
    
    FOR i IN 1..collection_variable.COUNT
    LOOP
        DBMS_OUTPUT.PUT_LINE(collection_variable(i).col1+6);
    END LOOP;
    
    collection_variable := null;
    EXECUTE IMMEDIATE 'SELECT * FROM bulk_collect_table' BULK COLLECT INTO collection_variable;
    
    FOR i IN 1..collection_variable.COUNT
    LOOP
        DBMS_OUTPUT.PUT_LINE(collection_variable(i).col1+12);
    END LOOP;
END;
/

CALL bulk_collect_procedure();