Need guidance in query optimization

Question

hi everyone.
This query takes more than 400 milli seconds to execute.it executes more than 25 times.make the web page slow.
can anyone provide guidance in optimizing this query
SELECT
     DISTINCT *
FROM
     PRICING_ANALYST
WHERE
     USER_ID IN
          SELECT
          FROM      
               PRICING_ANALYST pa,
               ALC_PROJECT p,
               REQUEST r,
               ALCG_TEMP_QUOTE q,
               ALC_USER u,
               REQUESTER, ALC_COUNTRY
          WHERE
               r.REQUEST_ID = 172938
               AND
               r.temp_quote_ref_num = q.temp_quote_ref_num
               AND
               r.user_id = q.user_id
               AND
               r.project_id = q.project_id
               AND
               pa.country_code = q.country_code
               AND
               q.country_code = alc_country.country_code
               AND
               p.project_id = r.project_id
               AND
               pa.user_id = u.user_id
               AND
               requester.user_id = p.user_id
               AND
               requester.project_id = p.project_id
               AND
                    pa.CUSTOMER_EQUANT = 'Y'
                    OR
                    pa.CUSTOMER_NEW_EQUANT = 'Y'
                    OR
                    pa.CUSTOMER_EXISTING_EQUANT = 'Y'
                    OR
                    pa.CUSTOMER_EXISTING_GLOBALONE = 'Y'
                    OR
                    pa.CUSTOMER_OTHERS = 'Y'
                    OR
                    pa.CUSTOMER_FRANCE_TELECOM = 'Y'
                    OR
                    pa.CUSTOMER_SPRINT = 'Y'
               AND
               pa.COUNTRY_CODE = q.COUNTRY_CODE
               AND
                    pa.Business_Opportunity IS null
                    OR
                    substr(pa.Business_Opportunity, instr(pa.Business_Opportunity,(r.Business_Opportunity || '''')), length(r.Business_Opportunity))= r.Business_Opportunity)
                    AND
                    pa.REQUEST_local_loop = 'Y'
                    AND
                    substr(pa.ACCESS_TECH_ID, instr(pa.ACCESS_TECH_ID, (q.ACCESS_TECH_ID || '''')), length(q.ACCESS_TECH_ID)) = q.ACCESS_TECH_ID
               )

Answer 1

Hi,
Pl make sure all tables related to this query are analyzed recently with indexes, try to preserve the explain plan of the queries when it is running properly, so we can compare if slow running query, any change in the plan.
Dilipkumar Patel