[Solved] How to improve the efficiency of below query?

How to optimize this SQL query?

In case you have your own slow SQL query, you can optimize it automatically here.

For the query above, the following recommendations will be helpful as part of the SQL tuning process.
You'll find 3 sections below:

  1. Description of the steps you can take to speed up the query.
  2. The optimal indexes for this query, which you can copy and create in your database.
  3. An automatically re-written query you can copy and execute in your database.
The optimization process and recommendations:
  1. Avoid Subqueries (query line: 40): We advise against using subqueries as they are not optimized well by the optimizer. Therefore, it's recommended to join a newly created temporary table that holds the data, which also includes the relevant search index.
The optimized query:
SELECT
        fcr.request_id,
        DECODE(fcpt.user_concurrent_program_name,
        'Report Set',
        fcr.description,
        'Request Set Stage',
        fcr.description,
        fcpt.user_concurrent_program_name) user_concurrent_program_name,
        fcr.description,
        fcr.argument_text,
        fcr.concurrent_program_id,
        fcr.parent_request_id,
        fcr.actual_start_date,
        fcr.actual_completion_date,
        ROUND((fcr.actual_completion_date - fcr.actual_start_date) * 24 * 60,
        4) runtime,
        DECODE(fcr.phase_code,
        'C',
        'No Schedule') program_status,
        fu.user_name,
        frt.responsibility_name,
        fcr.logfile_name 
    FROM
        [email protected]_link fcr,
        [email protected]_link fcpt,
        [email protected]_link fu,
        [email protected]_link frt 
    WHERE
        fcr.concurrent_program_id = fcpt.concurrent_program_id 
        AND fcr.requested_by = fu.user_id 
        AND fcr.responsibility_id = frt.responsibility_id 
        AND fcr.responsibility_application_id = frt.application_id 
        AND fcr.phase_code = 'C' 
        AND fcr.status_code IN (
            'C', 'G', 'E', 'X'
        ) 
        AND fcr.actual_completion_date >= SYSDATE - 1 / 24 
        AND fcr.requested_by = 1508715 
        AND fcr.request_id NOT IN (
            SELECT
                [email protected]_link.parent_request_id 
            FROM
                [email protected]_link
        )

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* original question posted on StackOverflow here.