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Make get_events_around more efficient on sqlite3

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This commit is contained in:
Mark Haines 2016-07-05 13:55:18 +01:00
parent d44d11d864
commit b6b0132ac7
1 changed files with 49 additions and 13 deletions
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42
synapse/storage/stream.py
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@ -40,7 +40,7 @@ from synapse.util.caches.descriptors import cached
from synapse.api.constants import EventTypes
from synapse.types import RoomStreamToken
from synapse.util.logcontext import preserve_fn
from synapse.storage.engines import PostgresEngine
from synapse.storage.engines import PostgresEngine, Sqlite3Engine
import logging
@ -614,19 +614,55 @@ class StreamStore(SQLBaseStore):
results["stream_ordering"],
)
if isinstance(self.database_engine, Sqlite3Engine):
# SQLite3 doesn't optimise ``(x < a) OR (x = a AND y < b)``
# So we give pass it to SQLite3 as the UNION ALL of the two queries.
query_before = (
"SELECT topological_ordering, stream_ordering, event_id FROM events"
" WHERE room_id = ? AND topological_ordering < ?"
" UNION ALL"
" SELECT topological_ordering, stream_ordering, event_id FROM events"
" WHERE room_id = ? AND topological_ordering = ? AND stream_ordering < ?"
" ORDER BY topological_ordering DESC, stream_ordering DESC LIMIT ?"
)
before_args = (
room_id, token.topological,
room_id, token.topological, token.stream,
before_limit,
)
query_after = (
"SELECT topological_ordering, stream_ordering, event_id FROM events"
" WHERE room_id = ? AND topological_ordering > ?"
" UNION ALL"
" SELECT topological_ordering, stream_ordering, event_id FROM events"
" WHERE room_id = ? AND topological_ordering = ? AND stream_ordering > ?"
" ORDER BY topological_ordering ASC, stream_ordering ASC LIMIT ?"
)
after_args = (
room_id, token.topological,
room_id, token.topological, token.stream,
after_limit,
)
else:
query_before = (
"SELECT topological_ordering, stream_ordering, event_id FROM events"
" WHERE room_id = ? AND %s"
" ORDER BY topological_ordering DESC, stream_ordering DESC LIMIT ?"
) % (upper_bound(token, self.database_engine, inclusive=False),)
before_args = (room_id, before_limit),
query_after = (
"SELECT topological_ordering, stream_ordering, event_id FROM events"
" WHERE room_id = ? AND %s"
" ORDER BY topological_ordering ASC, stream_ordering ASC LIMIT ?"
) % (lower_bound(token, self.database_engine, inclusive=False),)
txn.execute(query_before, (room_id, before_limit))
after_args = (room_id, after_limit)
txn.execute(query_before, before_args)
rows = self.cursor_to_dict(txn)
events_before = [r["event_id"] for r in rows]
@ -642,7 +678,7 @@ class StreamStore(SQLBaseStore):
token.stream - 1,
))
txn.execute(query_after, (room_id, after_limit))
txn.execute(query_after, after_args)
rows = self.cursor_to_dict(txn)
events_after = [r["event_id"] for r in rows]