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Optimize filter_events_for_client for faster /messages - v2 (#14527)

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Fix #14108
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Eric Eastwood 2022-11-22 15:56:28 -06:00 committed by GitHub
parent df390a8e67
commit 7f78b383ca
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2 changed files with 80 additions and 20 deletions
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changelog.d/14527.misc Normal file
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@ -0,0 +1 @@
Speed-up `/messages` with `filter_events_for_client` optimizations.

89
synapse/storage/databases/state/bg_updates.py
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@ -93,13 +93,6 @@ class StateGroupBackgroundUpdateStore(SQLBaseStore):
results: Dict[int, MutableStateMap[str]] = {group: {} for group in groups}
where_clause, where_args = state_filter.make_sql_filter_clause()
# Unless the filter clause is empty, we're going to append it after an
# existing where clause
if where_clause:
where_clause = " AND (%s)" % (where_clause,)
if isinstance(self.database_engine, PostgresEngine):
# Temporarily disable sequential scans in this transaction. This is
# a temporary hack until we can add the right indices in
@ -110,31 +103,91 @@ class StateGroupBackgroundUpdateStore(SQLBaseStore):
# against `state_groups_state` to fetch the latest state.
# It assumes that previous state groups are always numerically
# lesser.
# The PARTITION is used to get the event_id in the greatest state
# group for the given type, state_key.
# This may return multiple rows per (type, state_key), but last_value
# should be the same.
sql = """
WITH RECURSIVE state(state_group) AS (
WITH RECURSIVE sgs(state_group) AS (
VALUES(?::bigint)
UNION ALL
SELECT prev_state_group FROM state_group_edges e, state s
SELECT prev_state_group FROM state_group_edges e, sgs s
WHERE s.state_group = e.state_group
)
%s
"""
overall_select_query_args: List[Union[int, str]] = []
# This is an optimization to create a select clause per-condition. This
# makes the query planner a lot smarter on what rows should pull out in the
# first place and we end up with something that takes 10x less time to get a
# result.
use_condition_optimization = (
not state_filter.include_others and not state_filter.is_full()
)
state_filter_condition_combos: List[Tuple[str, Optional[str]]] = []
# We don't need to caclculate this list if we're not using the condition
# optimization
if use_condition_optimization:
for etype, state_keys in state_filter.types.items():
if state_keys is None:
state_filter_condition_combos.append((etype, None))
else:
for state_key in state_keys:
state_filter_condition_combos.append((etype, state_key))
# And here is the optimization itself. We don't want to do the optimization
# if there are too many individual conditions. 10 is an arbitrary number
# with no testing behind it but we do know that we specifically made this
# optimization for when we grab the necessary state out for
# `filter_events_for_client` which just uses 2 conditions
# (`EventTypes.RoomHistoryVisibility` and `EventTypes.Member`).
if use_condition_optimization and len(state_filter_condition_combos) < 10:
select_clause_list: List[str] = []
for etype, skey in state_filter_condition_combos:
if skey is None:
where_clause = "(type = ?)"
overall_select_query_args.extend([etype])
else:
where_clause = "(type = ? AND state_key = ?)"
overall_select_query_args.extend([etype, skey])
select_clause_list.append(
f"""
(
SELECT DISTINCT ON (type, state_key)
type, state_key, event_id
FROM state_groups_state
INNER JOIN sgs USING (state_group)
WHERE {where_clause}
ORDER BY type, state_key, state_group DESC
)
"""
)
overall_select_clause = " UNION ".join(select_clause_list)
else:
where_clause, where_args = state_filter.make_sql_filter_clause()
# Unless the filter clause is empty, we're going to append it after an
# existing where clause
if where_clause:
where_clause = " AND (%s)" % (where_clause,)
overall_select_query_args.extend(where_args)
overall_select_clause = f"""
SELECT DISTINCT ON (type, state_key)
type, state_key, event_id
FROM state_groups_state
WHERE state_group IN (
SELECT state_group FROM state
) %s
SELECT state_group FROM sgs
) {where_clause}
ORDER BY type, state_key, state_group DESC
"""
for group in groups:
args: List[Union[int, str]] = [group]
args.extend(where_args)
args.extend(overall_select_query_args)
txn.execute(sql % (where_clause,), args)
txn.execute(sql % (overall_select_clause,), args)
for row in txn:
typ, state_key, event_id = row
key = (intern_string(typ), intern_string(state_key))
@ -142,6 +195,12 @@ class StateGroupBackgroundUpdateStore(SQLBaseStore):
else:
max_entries_returned = state_filter.max_entries_returned()
where_clause, where_args = state_filter.make_sql_filter_clause()
# Unless the filter clause is empty, we're going to append it after an
# existing where clause
if where_clause:
where_clause = " AND (%s)" % (where_clause,)
# We don't use WITH RECURSIVE on sqlite3 as there are distributions
# that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
for group in groups: