Use `received_ts` to find uncensored redacted events
Joining against `events` and ordering by `stream_ordering` is
inefficient as it forced scanning the entirety of the redactions table.
This isn't the case if we use `redactions.received_ts` column as we can
then use an index.
1 files changed, 7 insertions, 14 deletions
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 3104815f1a..2e485c8644 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -1589,36 +1589,29 @@ class EventsStore(
if self.hs.config.redaction_retention_period is None:
return
- max_pos = yield self.find_first_stream_ordering_after_ts(
- self._clock.time_msec() - self.hs.config.redaction_retention_period
- )
+ before_ts = self._clock.time_msec() - self.hs.config.redaction_retention_period
# We fetch all redactions that:
# 1. point to an event we have,
- # 2. has a stream ordering from before the cut off, and
+ # 2. has a received_ts from before the cut off, and
# 3. we haven't yet censored.
#
# This is limited to 100 events to ensure that we don't try and do too
# much at once. We'll get called again so this should eventually catch
# up.
- #
- # We use the range [-max_pos, max_pos] to handle backfilled events,
- # which are given negative stream ordering.
sql = """
- SELECT redact_event.event_id, redacts FROM redactions
- INNER JOIN events AS redact_event USING (event_id)
+ SELECT redactions.event_id, redacts FROM redactions
LEFT JOIN events AS original_event ON (
- redact_event.room_id = original_event.room_id
- AND redacts = original_event.event_id
+ redacts = original_event.event_id
)
WHERE NOT have_censored
- AND ? <= redact_event.stream_ordering AND redact_event.stream_ordering <= ?
- ORDER BY redact_event.stream_ordering ASC
+ AND redactions.received_ts <= ?
+ ORDER BY redactions.received_ts ASC
LIMIT ?
"""
rows = yield self._execute(
- "_censor_redactions_fetch", None, sql, -max_pos, max_pos, 100
+ "_censor_redactions_fetch", None, sql, before_ts, 100
)
updates = []
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