Add additional indicies on event and review tables. Every events or timeline endpoint filters on event start time and camera, this should speed things up by avoiding a range scan on the table.

migrations/036_add_perf_indexes.py

@@ -0,0 +1,37 @@
+"""Peewee migrations -- 036_add_perf_indexes.py.
+
+Adds composite/single-column indexes to speed up the most common queries
+issued by the web UI on initial page load:
+
+- event(camera, start_time DESC): /events list filtered by camera + time range
+- reviewsegment(camera, start_time DESC): /api/review filtered by camera + time range
+- reviewsegment(end_time): supports the end_time > after half of /api/review's range
+
+The existing event(label, start_time DESC) index from migration 027 already
+covers /events/explore, so it is intentionally not duplicated here.
+"""
+
+import peewee as pw
+
+SQL = pw.SQL
+
+
+def migrate(migrator, database, fake=False, **kwargs):
+    migrator.sql(
+        'CREATE INDEX IF NOT EXISTS "event_camera_start_time" '
+        'ON "event" ("camera", "start_time" DESC)'
+    )
+    migrator.sql(
+        'CREATE INDEX IF NOT EXISTS "reviewsegment_camera_start_time" '
+        'ON "reviewsegment" ("camera", "start_time" DESC)'
+    )
+    migrator.sql(
+        'CREATE INDEX IF NOT EXISTS "reviewsegment_end_time" '
+        'ON "reviewsegment" ("end_time")'
+    )
+
+
+def rollback(migrator, database, fake=False, **kwargs):
+    migrator.sql('DROP INDEX IF EXISTS "event_camera_start_time"')
+    migrator.sql('DROP INDEX IF EXISTS "reviewsegment_camera_start_time"')
+    migrator.sql('DROP INDEX IF EXISTS "reviewsegment_end_time"')