Purge chain cover tables when purging events. (#9498)

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Patrick Cloke 2021-03-03 11:04:08 -05:00 committed by GitHub
parent d790d0d314
commit 922788c604
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3 changed files with 38 additions and 10 deletions

1
changelog.d/9498.bugfix Normal file
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@ -0,0 +1 @@
Properly purge the event chain cover index when purging history.

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@ -28,7 +28,10 @@ class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
async def purge_history(
self, room_id: str, token: str, delete_local_events: bool
) -> Set[int]:
"""Deletes room history before a certain point
"""Deletes room history before a certain point.
Note that only a single purge can occur at once, this is guaranteed via
a higher level (in the PaginationHandler).
Args:
room_id:
@ -52,7 +55,9 @@ class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
delete_local_events,
)
def _purge_history_txn(self, txn, room_id, token, delete_local_events):
def _purge_history_txn(
self, txn, room_id: str, token: RoomStreamToken, delete_local_events: bool
) -> Set[int]:
# Tables that should be pruned:
# event_auth
# event_backward_extremities
@ -103,7 +108,7 @@ class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
if max_depth < token.topological:
# We need to ensure we don't delete all the events from the database
# otherwise we wouldn't be able to send any events (due to not
# having any backwards extremeties)
# having any backwards extremities)
raise SynapseError(
400, "topological_ordering is greater than forward extremeties"
)
@ -154,7 +159,7 @@ class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
logger.info("[purge] Finding new backward extremities")
# We calculate the new entries for the backward extremeties by finding
# We calculate the new entries for the backward extremities by finding
# events to be purged that are pointed to by events we're not going to
# purge.
txn.execute(
@ -296,7 +301,7 @@ class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
"purge_room", self._purge_room_txn, room_id
)
def _purge_room_txn(self, txn, room_id):
def _purge_room_txn(self, txn, room_id: str) -> List[int]:
# First we fetch all the state groups that should be deleted, before
# we delete that information.
txn.execute(
@ -310,6 +315,31 @@ class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
state_groups = [row[0] for row in txn]
# Get all the auth chains that are referenced by events that are to be
# deleted.
txn.execute(
"""
SELECT chain_id, sequence_number FROM events
LEFT JOIN event_auth_chains USING (event_id)
WHERE room_id = ?
""",
(room_id,),
)
referenced_chain_id_tuples = list(txn)
logger.info("[purge] removing events from event_auth_chain_links")
txn.executemany(
"""
DELETE FROM event_auth_chain_links WHERE
(origin_chain_id = ? AND origin_sequence_number = ?) OR
(target_chain_id = ? AND target_sequence_number = ?)
""",
(
(chain_id, seq_num, chain_id, seq_num)
for (chain_id, seq_num) in referenced_chain_id_tuples
),
)
# Now we delete tables which lack an index on room_id but have one on event_id
for table in (
"event_auth",
@ -319,6 +349,8 @@ class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
"event_reference_hashes",
"event_relations",
"event_to_state_groups",
"event_auth_chains",
"event_auth_chain_to_calculate",
"redactions",
"rejections",
"state_events",

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@ -73,9 +73,6 @@ class PurgeEventsStorage:
Returns:
The set of state groups that can be deleted.
"""
# Graph of state group -> previous group
graph = {}
# Set of events that we have found to be referenced by events
referenced_groups = set()
@ -111,8 +108,6 @@ class PurgeEventsStorage:
next_to_search |= prevs
state_groups_seen |= prevs
graph.update(edges)
to_delete = state_groups_seen - referenced_groups
return to_delete