Commits on Jan 9, 2023

1. Add index to events table to help with 'jump to date' …

   Before
   
   ```sql
   synapse=> explain             SELECT event_id FROM events
               LEFT JOIN rejections USING (event_id)
               WHERE
                   room_id = '!...:matrix.org'
                   AND origin_server_ts <= 1620172800000
                   /**
                    * Make sure the event isn't an `outlier` because we have no way
                    * to later check whether it's next to a gap. `outliers` do not
                    * have entries in the `event_edges`, `event_forward_extremeties`,
                    * and `event_backward_extremities` tables to check against
                    * (used by `is_event_next_to_backward_gap` and `is_event_next_to_forward_gap`).
                    */
                   AND NOT outlier
                   /* Make sure event is not rejected */
                   AND rejections.event_id IS NULL
               /**
                * First sort by the message timestamp. If the message timestamps are the
                * same, we want the message that logically comes "next" (before/after
                * the given timestamp) based on the DAG and its topological order (`depth`).
                * Finally, we can tie-break based on when it was received on the server
                * (`stream_ordering`).
                */
               ORDER BY origin_server_ts DESC, depth DESC, stream_ordering DESC
               LIMIT 1;
                                                       QUERY PLAN
   ------------------------------------------------------------------------------------------------------------------
    Limit  (cost=1075.38..2148.31 rows=1 width=66)
      ->  Incremental Sort  (cost=1075.38..650197.88 rows=605 width=66)
            Sort Key: events.origin_server_ts DESC, events.depth DESC, events.stream_ordering DESC
            Presorted Key: events.origin_server_ts
            ->  Nested Loop Anti Join  (cost=0.71..650170.66 rows=605 width=66)
                  ->  Index Scan Backward using events_ts on events  (cost=0.43..649835.91 rows=605 width=66)
                        Index Cond: (origin_server_ts <= '1620172800000'::bigint)
                        Filter: ((NOT outlier) AND (room_id = '!...:matrix.org'::text))
                  ->  Index Only Scan using rejections_event_id_key on rejections  (cost=0.28..0.55 rows=1 width=41)
                        Index Cond: (event_id = events.event_id)
   ```
   
   Index
   
   ```sql
   synapse=> create index rei_jtd_idx ON events(room_id, origin_server_ts) WHERE not outlier;
   CREATE INDEX
   synapse=> explain             SELECT event_id FROM events
               LEFT JOIN rejections USING (event_id)
               WHERE
                   room_id = '!...:matrix.org'
                   AND origin_server_ts <= 1620172800000
                   /**
                    * Make sure the event isn't an `outlier` because we have no way
                    * to later check whether it's next to a gap. `outliers` do not
                    * have entries in the `event_edges`, `event_forward_extremeties`,
                    * and `event_backward_extremities` tables to check against
                    * (used by `is_event_next_to_backward_gap` and `is_event_next_to_forward_gap`).
                    */
                   AND NOT outlier
                   /* Make sure event is not rejected */
                   AND rejections.event_id IS NULL
               /**
                * First sort by the message timestamp. If the message timestamps are the
                * same, we want the message that logically comes "next" (before/after
                * the given timestamp) based on the DAG and its topological order (`depth`).
                * Finally, we can tie-break based on when it was received on the server
                * (`stream_ordering`).
                */
               ORDER BY origin_server_ts DESC, depth DESC, stream_ordering DESC
               LIMIT 1;
                                                                  QUERY PLAN
   ----------------------------------------------------------------------------------------------------------------------------------------
    Limit  (cost=5.44..10.08 rows=1 width=66)
      ->  Incremental Sort  (cost=5.44..2819.10 rows=607 width=66)
            Sort Key: events.origin_server_ts DESC, events.depth DESC, events.stream_ordering DESC
            Presorted Key: events.origin_server_ts
            ->  Nested Loop Anti Join  (cost=0.83..2791.78 rows=607 width=66)
                  ->  Index Scan Backward using rei_jtd_idx on events  (cost=0.56..2456.44 rows=607 width=66)
                        Index Cond: ((room_id = '!...:matrix.org'::text) AND (origin_server_ts <= '1620172800000'::bigint))
                  ->  Index Only Scan using rejections_event_id_key on rejections  (cost=0.28..0.55 rows=1 width=41)
                        Index Cond: (event_id = events.event_id)
   ```

   

   reivilibre committed Jan 9, 2023
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2. Newsfile …

   Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>

   

   reivilibre committed Jan 9, 2023
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