rspec/rules/S2449/plsql/rule.adoc

== Why is this an issue?

A ``++FETCH ... BULK COLLECT INTO++`` without a ``++LIMIT++`` clause will load all the records returned by the cursor at once. This may lead to memory exhaustion. Instead, it is better to process the records in chunks using the ``++LIMIT++`` clause.


=== Noncompliant code example

[source,sql]
----
SET SERVEROUTPUT ON

-- Fetches all records at once, requiring lots of memory
DECLARE
  TYPE largeTableRowArrayType IS TABLE OF largeTable%ROWTYPE;
  largeTableRowArray largeTableRowArrayType;
  CURSOR myCursor IS SELECT * FROM largeTable;
BEGIN
  OPEN myCursor;

  FETCH myCursor BULK COLLECT INTO largeTableRowArray; -- Non-compliant

  DBMS_OUTPUT.PUT_LINE('Alternative 1: ' || largeTableRowArray.COUNT || ' records');

  CLOSE myCursor;
END;
/
----


=== Compliant solution

[source,sql]
----
SET SERVEROUTPUT ON

-- fetches one chunk at a time, requiring constant memory
DECLARE
  TYPE largeTableRowArrayType IS TABLE OF largeTable%ROWTYPE;
  largeTableRowArray largeTableRowArrayType;
  CURSOR myCursor IS SELECT * FROM largeTable;
  counter PLS_INTEGER := 0;
BEGIN
  OPEN myCursor;

  LOOP
    FETCH myCursor BULK COLLECT INTO largeTableRowArray LIMIT 1000; -- Compliant

    counter := counter + largeTableRowArray.COUNT;

    EXIT WHEN myCursor%NOTFOUND;
  END LOOP;

  DBMS_OUTPUT.PUT_LINE('Alternative 1: ' || counter || ' records');

  CLOSE myCursor;
END;
/

DROP TABLE largeTable;
----

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Add a "LIMIT" clause to the statement.


endif::env-github,rspecator-view[]