Fix DB query on startup for negative streams. (#8447)

For negative streams we have to negate the internal stream ID before querying the DB. The effect of this bug was to query far too many rows, slowing start up time, but we would correctly filter the results afterwards so there was no ill effect.
matrix-org · Oct 2, 2020 · 695240d · 695240d
1 parent 34ff8da
commit 695240d
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diff --git a/changelog.d/8447.bugfix b/changelog.d/8447.bugfix
@@ -0,0 +1 @@
+Fix DB query on startup for negative streams which caused long start up times. Introduced in #8374.
diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
@@ -341,7 +341,7 @@ def _load_current_ids(
                 "cmp": "<=" if self._positive else ">=",
             }
             sql = self._db.engine.convert_param_style(sql)
-            cur.execute(sql, (min_stream_id,))
+            cur.execute(sql, (min_stream_id * self._return_factor,))
 
             self._persisted_upto_position = min_stream_id
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fix DB query on startup for negative streams which caused long start up times. Introduced in #8374.