How to improve Performace of this data.

Question

Hi All,
We have ticket_master table with 200,000 currently and grows 2000 records per day. structure is
ticket_no VARCHAR2(20) PK,
trip_id VARCHAR2(20) RK refers to trip_master(trip_id),
passenger_name,fare,boarding etc...
second table is Ticket_cancellations currently 5000 records and daily it gets 50 records minimum.
Ticket_no RK references to TIcket_master(ticket_no),
cancellation_charges.... etc.
like if we need to see list of passengers for any trip we are querying like this
SELECT ticket_no,name_of_the_passenger.. FROM ticket_master WHERE ticket_no NOT IN (SELECT Ticket_no FROM ticket_cancellations) WHERE trip_id = my_trip_id;
it seems the performance is getting reduced with the growing size of both tables.
Is there any way we can improve this performace. we have indexes created on both tables.
Thanks in advance

Answer 1

I agree.
SELECT ticket_no,name_of_the_passenger..
FROM ticket_master
WHERE ticket_no NOT IN
(SELECT Ticket_no
FROM ticket_cancellations
WHERE trip_id = my_trip_id);
This involves creating a little temp table for each record in ticket_no. Then full scanning it.
Change it to
SELECT ticket_no,name_of_the_passenger..
FROM ticket_master B
WHERE ticket_no NOT EXISTS
(SELECT null
FROM ticket_cancellations A
WHERE A.ticket_no = B.ticket_no
AND trip_id = my_trip_id);
Then you get an index hit in both cases.