Using IF with FORALL.

Question

Hi
I was having a normal cursor and i was looping through it and inserting rows in 3 different tables based on the values.
I was using IF condition in the cursor.
I want to change the For to FORALL using Bulk Fetch so that the performance is improved. But at the same time as i am inserting in 3 tables based on values, how do i use IF condition with FORALL.
I believe, i will have to open 3 cursors and Bulk Fetch and use FOR ALL 3 times, which will not improve my performance.
I am working on oracle 9i v2 and on an average the number of rows would be around 70000
Any Suggestions ???
Regards
Nikhil

Answer 1

We can do this with a multi-table INSERT and FORALL. For demo, I've created three tables, T1-3. T1 will hold all our table names, T2 our index names and T3 every other object name.
SQL> CREATE TABLE t1 ( c1 INT, c2 VARCHAR2(30) );
Table created.
SQL> CREATE TABLE t2 ( c1 INT, c2 VARCHAR2(30) );
Table created.
SQL> CREATE TABLE t3 ( c1 INT, c2 VARCHAR2(30) );
Table created.We'll BULK COLLECT some dummy data and then conditionally INSERT it into T1, T2 or T3...
SQL> DECLARE
  2 
  3     /* Associative array types and variables... */
  4     TYPE aat_id IS TABLE OF user_objects.object_id%TYPE
  5        INDEX BY PLS_INTEGER;
  6     TYPE aat_name IS TABLE OF user_objects.object_name%TYPE
  7        INDEX BY PLS_INTEGER;
  8     TYPE aat_type IS TABLE OF user_objects.object_type%TYPE
  9        INDEX BY PLS_INTEGER;
10     aa_ids aat_id;
11     aa_names aat_name;
12     aa_types aat_type;
13 
14  BEGIN
15 
16     /* SELECT brings three different types of records... */
17     SELECT object_id, object_name, object_type
18     BULK COLLECT INTO aa_ids, aa_names, aa_types
19     FROM user_objects;
20 
21     /* Conditional FORALL INSERT... */
22     FORALL i IN aa_ids.FIRST .. aa_ids.LAST
23        INSERT ALL
24           WHEN aa_types(i) = 'TABLE'
25              THEN INTO t1 VALUES ( aa_ids(i), aa_names(i) )
26           WHEN aa_types(i) = 'INDEX'
27              THEN INTO t2 VALUES ( aa_ids(i), aa_names(i) )
28           WHEN aa_types(i) NOT IN ( 'TABLE', 'INDEX' )
29              THEN INTO t3 VALUES ( aa_ids(i), aa_names(i) )
30        SELECT dummy FROM dual;
31 
32  END;
33  /
PL/SQL procedure successfully completed.
SQL>
SQL> SELECT 'USER_OBJECTS', COUNT(*) FROM user_objects WHERE object_type = 'TABLE'
  2  UNION ALL
  3  SELECT 'T1', COUNT(*) FROM t1;
'USER_OBJECT   COUNT(*)
USER_OBJECTS         26
T1                   26
SQL>
SQL> SELECT 'USER_OBJECTS', COUNT(*) FROM user_objects WHERE object_type = 'INDEX'
  2  UNION ALL
  3  SELECT 'T1', COUNT(*) FROM t2;
'USER_OBJECT   COUNT(*)
USER_OBJECTS          3
T1                    3
SQL>
SQL> SELECT 'USER_OBJECTS', COUNT(*) FROM user_objects WHERE object_type NOT IN ( 'TABLE', 'INDEX' )
  2  UNION ALL
  3  SELECT 'T1', COUNT(*) FROM t3;
'USER_OBJECT   COUNT(*)
USER_OBJECTS         20
T1                   20Regards
Adrian