How to build cursor based on an array - arrays

Question

I need to optimize a PL/SQL function that is currently like that:
CREATE OR REPLACE FUNCTION tkt_get_underlying(n_input number)
RETURN t_table_of_number
IS
ret t_table_of_number;
CURSOR c IS SELECT n_number FROM t_table WHERE n_prop_1=n_input OR n_prop_2=n_input OR n_prop_3=n_input;
BEGIN
ret := t_table_of_number();
OPEN c;
FETCH c BULK COLLECT INTO ret;
CLOSE c;
RETURN ret;
END;
I want to be able to give an array as argument, however, I don't know how to build my cursor to take to array. I think I could use the IN statement, but could you help me settle this down please ?
EDIT:
According to solution provided by Justin Cave, it would become:
CREATE OR REPLACE FUNCTION tkt_get_underlying(n_inputs t_table_of_number)
RETURN t_table_of_number
IS
ret t_table_of_number;
CURSOR c IS SELECT n_number FROM t_table WHERE n_prop_1 IN (SELECT column_value FROM TABLE(n_inputs))
OR n_prop_2 IN (SELECT column_value FROM TABLE(n_inputs))
OR n_prop_3 IN (SELECT column_value FROM TABLE(n_inputs));
BEGIN
ret := t_table_of_number();
OPEN c;
FETCH c BULK COLLECT INTO ret;
CLOSE c;
RETURN ret;
END;
However, the multiple SELECT column_value FROM TABLE(n_inputs) slow the entire function. How can I improve that ?

Answer 1

If you want to pass in a collection of n_input values and return the same t_table_of_number collection (i.e. you don't need to know which element of the output array was associated with which element of the input array)
CREATE OR REPLACE FUNCTION tkt_get_underlying(p_inputs t_table_of_number)
RETURN t_table_of_number
IS
ret t_table_of_number;
CURSOR c
IS SELECT n_number
FROM t_table
WHERE n_prop IN (SELECT column_value
FROM TABLE( p_inputs ) );
BEGIN
OPEN c;
FETCH c BULK COLLECT INTO ret;
CLOSE c;
RETURN ret;
END;
This assumes that the number of elements that is going to potentially be inserted into the ret collection is still reasonable to hold in PGA memory simultaneously. Depending on the situation, you may want to transform this into a pipelined table function in order to limit the amount of PGA memory required.

Answer 2

Oracle is getting the cardinality wrong using the nested table, since it will have no idea how many rows are actually there. Try making your function look like:
CREATE OR REPLACE FUNCTION tkt_get_underlying(n_inputs t_table_of_number)
RETURN t_table_of_number
IS
ret t_table_of_number;
CURSOR c IS SELECT n_number FROM t_table WHERE n_prop_1 IN (SELECT /*+ cardinality(ni 1) */ column_value FROM TABLE(n_inputs) ni)
OR n_prop_2 IN (SELECT /*+ cardinality(ni 1) */ column_value FROM TABLE(n_inputs) ni)
OR n_prop_3 IN (SELECT /*+ cardinality(ni 1) */ column_value FROM TABLE(n_inputs) ni);
BEGIN
ret := t_table_of_number();
OPEN c;
FETCH c BULK COLLECT INTO ret;
CLOSE c;
RETURN ret;
END;
Note, if you know how many rows you expect in the nested table, make your cardinality hint accurate. Also, if you put too many rows in the nested table, Oracle could perform sub-optimally because you are making it think there are less rows in the nested table than what it really has.

Answer 3

Thank you for all your help, I finally find THE optimization that fit my needs. Now the query is like:
CREATE OR REPLACE FUNCTION tkt_get_underlying(n_inputs t_table_of_number)
RETURN t_table_of_number
IS
ret t_table_of_number;
CURSOR c IS SELECT t.n_number FROM t_table t, (SELECT column_value /*+cardinality(t_inputs 100) */ c FROM TABLE(n_inputs)) t_inputs
WHERE t_inputs.c = t.n_prop_1
OR t_inputs.c = t.n_prop_2
OR t_inputs.c = t.n_prop_3;
BEGIN
ret := t_table_of_number();
OPEN c;
FETCH c BULK COLLECT INTO ret;
CLOSE c;
RETURN ret;
END;
It does a JOIN that is better than a IN