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Merge pull request #1144 from matrix-org/erikj/sqlite_state_perf

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Fix perf of fetching state in SQLite
This commit is contained in:
Erik Johnston 2016-09-27 11:22:45 +01:00 committed by GitHub
commit 4a18127917
1 changed files with 29 additions and 23 deletions
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52
synapse/storage/state.py
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@ -307,6 +307,9 @@ class StateStore(SQLBaseStore):
def _get_state_groups_from_groups_txn(self, txn, groups, types=None):
results = {group: {} for group in groups}
if types is not None:
types = list(set(types)) # deduplicate types list
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
@ -375,10 +378,35 @@ class StateStore(SQLBaseStore):
# 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:
group_tree = [group]
next_group = group
while next_group:
# We did this before by getting the list of group ids, and
# then passing that list to sqlite to get latest event for
# each (type, state_key). However, that was terribly slow
# without the right indicies (which we can't add until
# after we finish deduping state, which requires this func)
args = [next_group]
if types:
args.extend(i for typ in types for i in typ)
txn.execute(
"SELECT type, state_key, event_id FROM state_groups_state"
" WHERE state_group = ? %s" % (where_clause,),
args
)
rows = txn.fetchall()
results[group].update({
(typ, state_key): event_id
for typ, state_key, event_id in rows
if (typ, state_key) not in results[group]
})
# If the lengths match then we must have all the types,
# so no need to go walk further down the tree.
if types is not None and len(results[group]) == len(types):
break
next_group = self._simple_select_one_onecol_txn(
txn,
table="state_group_edges",
@ -386,28 +414,6 @@ class StateStore(SQLBaseStore):
retcol="prev_state_group",
allow_none=True,
)
if next_group:
group_tree.append(next_group)
sql = ("""
SELECT type, state_key, event_id FROM state_groups_state
INNER JOIN (
SELECT type, state_key, max(state_group) as state_group
FROM state_groups_state
WHERE state_group IN (%s) %s
GROUP BY type, state_key
) USING (type, state_key, state_group);
""") % (",".join("?" for _ in group_tree), where_clause,)
args = list(group_tree)
if types is not None:
args.extend([i for typ in types for i in typ])
txn.execute(sql, args)
rows = self.cursor_to_dict(txn)
for row in rows:
key = (row["type"], row["state_key"])
results[group][key] = row["event_id"]
return results