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Optimize getting the latest events in each room #436

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merged 3 commits into from
May 20, 2024
Merged

Optimize getting the latest events in each room #436

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3ca77f2
Optimize getting the latest events in each room
S7evinK May 17, 2024
1ae5b5c
Also optimize LatestEventNIDInRooms
S7evinK May 17, 2024
425ed4e
Fix order of params and tell pq what $1 is
S7evinK May 17, 2024
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51 changes: 42 additions & 9 deletions state/event_table.go
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Original file line number Diff line number Diff line change
Expand Up @@ -312,29 +312,62 @@ func (t *EventTable) UpdateBeforeSnapshotID(txn *sqlx.Tx, eventNID, snapID, repl
return err
}

// query the latest events in each of the room IDs given, using highestNID as the highest event.
// LatestEventInRooms queries the latest events in each of the room IDs given, using highestNID as the highest event.
//
// The following query does:
//
// 1. Create a list of the passed in roomIDs (`room_ids` CTE)
// 2. Fetches the highest event_nid before or equal to $2 for each room in room_ids (`max_ev_nid` CTE)
// 3. Fetches the latest events for each room using the data provided from room_ids and max_ev_nid (the `evs` LATERAL)
func (t *EventTable) LatestEventInRooms(txn *sqlx.Tx, roomIDs []string, highestNID int64) (events []Event, err error) {
// the position (event nid) may be for a random different room, so we need to find the highest nid <= this position for this room
err = txn.Select(
&events,
`SELECT event_nid, room_id, event_replaces_nid, before_state_snapshot_id, event_type, state_key, event FROM syncv3_events
WHERE event_nid IN (SELECT max(event_nid) FROM syncv3_events WHERE event_nid <= $1 AND room_id = ANY($2) GROUP BY room_id)`,
highestNID, pq.StringArray(roomIDs),
`
WITH room_ids AS (
select unnest($1::text[]) AS room_id
),
max_ev_nid AS (
SELECT *
FROM room_ids,
LATERAL (
SELECT max(event_nid) FROM syncv3_events e WHERE e.room_id = room_ids.room_id AND event_nid <= $2
) AS x)
SELECT evs.*
FROM room_ids,
max_ev_nid,
LATERAL (
SELECT event_nid, room_id, event_replaces_nid, before_state_snapshot_id, event_type, state_key, event
FROM syncv3_events e
WHERE e.event_nid = max_ev_nid.max AND room_ids.room_id = e.room_id
) AS evs`,
pq.StringArray(roomIDs), highestNID,
)
if err == sql.ErrNoRows {
err = nil
}
return
}

// LatestEventNIDInRooms queries the latest events in each of the room IDs given, using highestNID as the highest event.
//
// The following query does:
//
// 1. Create a list of the passed in roomIDs (`room_ids` CTE)
// 2. Fetches the latest eventNIDs for each room using the data provided from room_ids (the `evs` LATERAL)
func (t *EventTable) LatestEventNIDInRooms(txn *sqlx.Tx, roomIDs []string, highestNID int64) (roomToNID map[string]int64, err error) {
// the position (event nid) may be for a random different room, so we need to find the highest nid <= this position for this room
var events []Event
err = txn.Select(
&events,
`SELECT event_nid, room_id FROM syncv3_events
WHERE event_nid IN (SELECT max(event_nid) FROM syncv3_events WHERE event_nid <= $1 AND room_id = ANY($2) GROUP BY room_id)`,
highestNID, pq.StringArray(roomIDs),
`
WITH room_ids AS (
select unnest($1::text[]) AS room_id
)
SELECT evs.event_nid, room_id
FROM room_ids,
LATERAL (
SELECT max(event_nid) event_nid FROM syncv3_events e WHERE e.room_id = room_ids.room_id AND event_nid <= $2
) AS evs WHERE event_nid IS NOT NULL;`,
pq.StringArray(roomIDs), highestNID,
)
if err == sql.ErrNoRows {
err = nil
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