Performance issues kindly give your suggestions

Question

hai
i have master table for vehicle table name is VEHICLE. this table is the main table, this is having records (80 lakhs)
Engine has two tables ( ENGINE(master) and ENGINE_SUB( Details for engine) ( less number of records 200 records only)
Like wise GEAR has two tables ( GEAR (master) and GEAR_SUB( details for gear) ( less number of records 200 records only)
For me the query will get framed in RUNTIME
IF User select ( ENGINE='ENG-001' and GEAR='GEAR-001') then the query get framed in "WHERE" part is as below
(ENGINE.COL1='ENG-001'
ENGINE.COL2=VEHICLE.COL1
ENGINE.COL1=ENGINE_SUB.COL1
ENGINE_SUB.COL2=VEHICLE.COL2)
AND
( GEAR.COL1='GEAR-001'
GEAR.COL2=VEHICLE.COL1
GEAR.COL1=GEAR_SUB.COL1
GEAR_SUB.COL2=VEHICLE.COL2)Upto here there is no problem at all
PERFORMANCE COMES ONLY WHEN IF USER SELECT ( ENGINE='ENG-001' OR GEAR='GEAR-001') then the query get framed in "WHERE" part is as below
(ENGINE.COL1='ENG-001'
ENGINE.COL2=VEHICLE.COL1
ENGINE.COL1=ENGINE_SUB.COL1
ENGINE_SUB.COL2=VEHICLE.COL2)
OR 
( GEAR.COL1='GEAR-001'
GEAR.COL2=VEHICLE.COL1
GEAR.COL1=GEAR_SUB.COL1
GEAR_SUB.COL2=VEHICLE.COL2)this is taking much time to process. even 2 hours.
Index information
both the column of VEHICLE is indexed. VEHICLE has 80 lakhs record while other table has only 200 records. i dont have indexes in engine and gear tables.
So kindly help me
Waiting
S

Answer 1

... /* next block should be left outer joined */
AND ENGINE.COL2=VEHICLE.COL1
AND ENGINE.COL1=ENGINE_SUB.COL1
AND ENGINE_SUB.COL2=VEHICLE.COL2
... /* next block should be left outer joined */
AND GEAR.COL2=VEHICLE.COL1
AND GEAR.COL1=GEAR_SUB.COL1
AND GEAR_SUB.COL2=VEHICLE.COL
... /* where condition from the user */
AND (ENGINE.COL1='ENG-001' or GEAR.COL1='GEAR-001')
Hai
the above query u framed will give wrong number of results. AND (ENGINE.COL1='ENG-001' or GEAR.COL1='GEAR-001')
Because
1) if ur giving OR condition like above then ENGINE_SUB.COL2 and GEAR_SUB.COL2 has direct join with VEHICLE. then the result will be wrong. both these columns joins with VEHICLE irrespective of each other.
then it should be like this AND GEAR_SUB.COL2=VEHICLE.COL or GEAR_SUB.COL2=VEHICLE.COL
Hope you get my point
S