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Only join on event_labels if we're filtering on labels
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@ -871,23 +871,38 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
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args.append(int(limit))
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args.append(int(limit))
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# Using DISTINCT in this SELECT query is quite expensive, because it requires the
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# engine to sort on the entire (not limited) result set, i.e. the entire events
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# table. We only need to use it when we're filtering on more than two labels,
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# because that's the only scenario in which we can possibly to get multiple times
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# the same event ID in the results.
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select_keywords = "SELECT"
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select_keywords = "SELECT"
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if event_filter and event_filter.labels and len(event_filter.labels) > 1:
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join_clause = ""
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select_keywords += "DISTINCT"
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if event_filter and event_filter.labels:
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# If we're not filtering on a label, then joining on event_labels will
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# return as many row for a single event as the number of labels it has. To
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# avoid this, only join if we're filtering on at least one label.
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join_clause = (
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"LEFT JOIN event_labels"
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" USING (event_id, room_id, topological_ordering)"
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)
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if len(event_filter.labels) > 1:
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# Using DISTINCT in this SELECT query is quite expensive, because it
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# requires the engine to sort on the entire (not limited) result set,
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# i.e. the entire events table. We only need to use it when we're
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# filtering on more than two labels, because that's the only scenario
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# in which we can possibly to get multiple times the same event ID in
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# the results.
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select_keywords += "DISTINCT"
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sql = (
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sql = (
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"%(select_keywords)s event_id, topological_ordering, stream_ordering"
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"%(select_keywords)s event_id, topological_ordering, stream_ordering"
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" FROM events"
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" FROM events"
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" LEFT JOIN event_labels USING (event_id, room_id, topological_ordering)"
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" %(join_clause)s"
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" WHERE outlier = ? AND room_id = ? AND %(bounds)s"
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" WHERE outlier = ? AND room_id = ? AND %(bounds)s"
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" ORDER BY topological_ordering %(order)s,"
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" ORDER BY topological_ordering %(order)s,"
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" stream_ordering %(order)s LIMIT ?"
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" stream_ordering %(order)s LIMIT ?"
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) % {"select_keywords": select_keywords, "bounds": bounds, "order": order}
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) % {
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"select_keywords": select_keywords,
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"join_clause": join_clause,
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"bounds": bounds,
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"order": order
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}
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txn.execute(sql, args)
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txn.execute(sql, args)
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