Re: Query running slow for only one specific id. (Postgres 9.3) version

explain analyze SELECT max(last_update_date) AS last_update_date FROM btdt_responses WHERE registration_id = 8718704208 AND response != 4;

                                                                                QUERY PLAN

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Result  (cost=2902.98..2903.01 rows=1 width=0) (actual time=86910.730..86910.731 rows=1 loops=1)

   InitPlan 1 (returns $0)

     ->  Limit  (cost=0.57..2902.98 rows=1 width=8) (actual time=86910.725..86910.725 rows=1 loops=1)

           ->  Index Scan Backward using btdt_responses_n5 on btdt_responses  (cost=0.57..6425932.41 rows=2214 width=8) (actual time=86910.723..86910.723 rows=1 loops=1)

                 Index Cond: (last_update_date IS NOT NULL)

                 Filter: ((response <> 4) AND (registration_id = 8718704208::bigint))

                 Rows Removed by Filter: 52145434

Total runtime: 86910.766 ms