Bulk Cursor Helpers

These procedures and functions are used to simulate the behavior of a CURSOR with bulk operations.

You might also be interested in Default FORALL transformation.

The Cursor is simulated with an OBJECT with different information regarding the state of the cursor. A temporary table is created to store the result set of the cursor's query.

Most of these Procedures return a new Object with the updated state of the cursor.

INIT_CURSOR

This function initializes a new object with the basic cursor information

CREATE OR REPLACE FUNCTION INIT_CURSOR(NAME VARCHAR, QUERY VARCHAR)
RETURNS OBJECT
AS
$$
  SELECT OBJECT_CONSTRUCT('NAME', NAME, 'ROWCOUNT', -1, 'QUERY', QUERY, 'ISOPEN', FALSE, 'FOUND', NULL, 'NOTFOUND', NULL)
$$;

OPEN_BULK_CURSOR

These procedures creates a temporary table with the query of the cursor. An optional overload exists to support bindings.

CREATE OR REPLACE PROCEDURE OPEN_BULK_CURSOR(CURSOR OBJECT, BINDINGS ARRAY)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var query = `CREATE OR REPLACE TEMPORARY TABLE ${CURSOR.NAME}_TEMP_TABLE AS ${CURSOR.QUERY}`;
  snowflake.execute({ sqlText: query, binds: BINDINGS });
  CURSOR.ROWCOUNT = 0;
  CURSOR.ISOPEN = true;
  return CURSOR;
$$;
CREATE OR REPLACE PROCEDURE OPEN_BULK_CURSOR(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL OPEN_BULK_CURSOR(:CURSOR, NULL));
    RETURN :RESULT;
  END;
$$;

CLOSE_BULK_CURSOR

This procedure deletes the temporary table that stored the result set of the cursor and resets the cursor's properties to their initial state.

CREATE OR REPLACE PROCEDURE CLOSE_BULK_CURSOR(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var query = `DROP TABLE ${CURSOR.NAME}_TEMP_TABLE`;
  snowflake.execute({ sqlText: query });
  CURSOR.ROWCOUNT = -1;
  CURSOR.ISOPEN = false;
  CURSOR.FOUND = null;
  CURSOR.NOTFOUND = null;
  return CURSOR;
$$;

FETCH Helpers

Due to Oracle being capable of doing the FETCH statement on different kind of scenarios, a multiple procedures with overloads were created to handle each case. These helpers save the fetched values into the RESULT property in the CURSOR object.

Some of the overloads include variations when the LIMIT clause was used or not. Other overloads have a COLUMN_NAMES argument that is necessary when the FETCH statement is being done into a variable that has or contains a records with column names that are different to the column names of the query.

FETCH_BULK_COLLECTION_RECORDS

These procedures are used when a FETCH BULK is done into a collection of records.

CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT, LIMIT FLOAT, COLUMN_NAMES ARRAY)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER
AS
$$
  var objectConstructArgs = [];
  if (COLUMN_NAMES) {
    for (let i = 0 ; i < COLUMN_NAMES.length ; i++) {
      objectConstructArgs.push("'" + COLUMN_NAMES[i] + "'");
      objectConstructArgs.push('$' + (i + 1));
    }
  } else {
    objectConstructArgs.push('*');
  }
  var limitValue = LIMIT ?? 'NULL';
  var query = `SELECT ARRAY_AGG(OBJECT_CONSTRUCT(${objectConstructArgs.join(', ')})) FROM (SELECT * FROM ${CURSOR.NAME}_TEMP_TABLE LIMIT ${limitValue} OFFSET ${CURSOR.ROWCOUNT})`;
  var stmt = snowflake.createStatement({ sqlText: query});
  var resultSet = stmt.execute();
  resultSet.next();
  CURSOR.RESULT = resultSet.getColumnValue(1);
  CURSOR.ROWCOUNT += CURSOR.RESULT.length;
  CURSOR.FOUND = CURSOR.RESULT.length > 0;
  CURSOR.NOTFOUND = !CURSOR.FOUND;
  return CURSOR;
$$;
CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_COLLECTION_RECORDS(:CURSOR, NULL, NULL));
    RETURN :RESULT;
  END;
$$;
CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT, LIMIT INTEGER)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_COLLECTION_RECORDS(:CURSOR, :LIMIT, NULL));
    RETURN :RESULT;
  END;
$$;
CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTION_RECORDS(CURSOR OBJECT, COLUMN_NAMES ARRAY)
RETURNS OBJECT
LANGUAGE SQL
EXECUTE AS CALLER
AS
$$
  DECLARE
    RESULT OBJECT;
  BEGIN
    RESULT := (CALL FETCH_BULK_COLLECTION_RECORDS(:CURSOR, NULL, :COLUMN_NAMES));
    RETURN :RESULT;
  END;
$$;

FETCH_BULK_COLLECTIONS

These procedures are used when the FETCH statement is done into one or multiple collections. Since the columns are specified in this FETCH operation, an override for specific COLUMN_NAMES is not necessary.

CREATE OR REPLACE PROCEDURE FETCH_BULK_COLLECTIONS(CURSOR OBJECT, LIMIT FLOAT)
RETURNS OBJECT
LANGUAGE JAVASCRIPT
EXECUTE AS CALLER