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FETCH ... BULK COLLECT INTO should not be used without a LIMIT clause

Description

    The FETCH ... BULK COLLECT INTO code rule states that the FETCH ... BULK COLLECT INTO statement should not be used without a LIMIT clause. This is because the FETCH ... BULK COLLECT INTO statement can be used to retrieve a large number of rows from a database table, and without a LIMIT clause, it could retrieve an excessive amount of data, which could cause performance issues. Therefore, it is important to always include a LIMIT clause when using the FETCH ... BULK COLLECT INTO statement to ensure that only the necessary amount of data is retrieved.

Key Benefits

  • Reduced resource usage: Using the FETCH ... BULK COLLECT INTO should not be used without a LIMIT clause rule helps to reduce the amount of resources used by the database.
  • Improved performance: By limiting the number of rows retrieved, this rule helps to improve the performance of queries.
  • Preventing data overload: By setting a limit on the number of rows retrieved, this rule helps to prevent the database from being overwhelmed with too much data.

 

Non-compliant Code Example

DECLARE
limit PLS_INTEGER := 100;
CURSOR cur_dept (departmentId INTEGER) RETURN departments%ROWTYPE IS  -- Define cur_dept,
    SELECT * FROM departments              -- repeating return type
    WHERE department_id = departmentId;	
	
BEGIN
  OPEN cur_dept;
  FETCH cur_dept                --Non compliant code (FETCH clause used without LIMIT clause in BULK COLLECT)
  BULK COLLECT INTO temp1;
  IF NOT cur_dept%FOUND THEN  
    DBMS_OUTPUT.PUT_LINE('Not Found !!');
  ELSE
    DBMS_OUTPUT.PUT_LINE('Department Found: ' || temp1);
  END IF;
  CLOSE cur_dept;
END;

Compliant Code Example

DECLARE
limit PLS_INTEGER := 100;
CURSOR cur_dept (departmentId INTEGER) RETURN departments%ROWTYPE IS  -- Define cur_dept,
    SELECT * FROM departments              -- repeating return type
    WHERE department_id = departmentId;	
	
BEGIN
  OPEN cur_dept;
  FETCH cur_dept                --Compliant code (FETCH clause used with LIMIT clause in BULK COLLECT)
  BULK COLLECT INTO temp1
  LIMIT limit;
  IF NOT cur_dept%FOUND THEN  
    DBMS_OUTPUT.PUT_LINE('Not Found !!');
  ELSE
    DBMS_OUTPUT.PUT_LINE('Department Found: ' || temp1);
  END IF;
  CLOSE cur_dept;
END;
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 VEPLSQLRULE15