[Solved] How to optimize selection of pairs from one column of the table (self-join)?

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. Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.
Optimal indexes for this query:
CREATE INDEX example_idx_user_name_tm ON "example"."example" ("user_name","tm");
The optimized query:
        t.place_name AS r1_place,
        max(t.tm) AS r1_tm,
        t2.place_name AS r2_place,
        min(t2.tm) AS r2_tm 
        example.example AS t 
        example.example AS t2 
            ON t.user_name = t2.user_name 
            AND t.tm < t2.tm 
            AND t.place_name <> t2.place_name 
        t.tm BETWEEN '2020-02-25 00:00:00' AND '2020-03-25 15:00:00' 
        AND t2.tm BETWEEN '2020-02-25 00:00:00' AND '2020-03-25 15:00:00' 

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* original question posted on StackOverflow here.