Stop writing to the event_txn_id table (#16175)

6 files changed, 26 insertions, 95 deletions

diff --git a/changelog.d/16175.misc b/changelog.d/16175.misc
new file mode 100644
index 0000000000..308fbc2259
--- /dev/null
+++ b/changelog.d/16175.misc
@@ -0,0 +1 @@
+Stop using the `event_txn_id` table.
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 187c3e6cc0..d6be18cdef 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -908,19 +908,6 @@ class EventCreationHandler:
             if existing_event_id:
                 return existing_event_id
 
-        # Some requsters don't have device IDs (appservice, guests, and access
-        # tokens minted with the admin API), fallback to checking the access token
-        # ID, which should be close enough.
-        if requester.access_token_id:
-            existing_event_id = (
-                await self.store.get_event_id_from_transaction_id_and_token_id(
-                    room_id,
-                    requester.user.to_string(),
-                    requester.access_token_id,
-                    txn_id,
-                )
-            )
-
         return existing_event_id
 
     async def get_event_from_transaction(
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index c784612f59..0c1ed75240 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -978,26 +978,12 @@ class PersistEventsStore:
         """Persist the mapping from transaction IDs to event IDs (if defined)."""
 
         inserted_ts = self._clock.time_msec()
-        to_insert_token_id: List[Tuple[str, str, str, int, str, int]] = []
         to_insert_device_id: List[Tuple[str, str, str, str, str, int]] = []
         for event, _ in events_and_contexts:
             txn_id = getattr(event.internal_metadata, "txn_id", None)
-            token_id = getattr(event.internal_metadata, "token_id", None)
             device_id = getattr(event.internal_metadata, "device_id", None)
 
             if txn_id is not None:
-                if token_id is not None:
-                    to_insert_token_id.append(
-                        (
-                            event.event_id,
-                            event.room_id,
-                            event.sender,
-                            token_id,
-                            txn_id,
-                            inserted_ts,
-                        )
-                    )
-
                 if device_id is not None:
                     to_insert_device_id.append(
                         (
@@ -1010,26 +996,7 @@ class PersistEventsStore:
                         )
                     )
 
-        # Synapse usually relies on the device_id to scope transactions for events,
-        # except for users without device IDs (appservice, guests, and access
-        # tokens minted with the admin API) which use the access token ID instead.
-        #
-        # TODO https://github.com/matrix-org/synapse/issues/16042
-        if to_insert_token_id:
-            self.db_pool.simple_insert_many_txn(
-                txn,
-                table="event_txn_id",
-                keys=(
-                    "event_id",
-                    "room_id",
-                    "user_id",
-                    "token_id",
-                    "txn_id",
-                    "inserted_ts",
-                ),
-                values=to_insert_token_id,
-            )
-
+        # Synapse relies on the device_id to scope transactions for events..
         if to_insert_device_id:
             self.db_pool.simple_insert_many_txn(
                 txn,
diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py
index 7e7648c951..1eb313040e 100644
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -2022,25 +2022,6 @@ class EventsWorkerStore(SQLBaseStore):
             desc="get_next_event_to_expire", func=get_next_event_to_expire_txn
         )
 
-    async def get_event_id_from_transaction_id_and_token_id(
-        self, room_id: str, user_id: str, token_id: int, txn_id: str
-    ) -> Optional[str]:
-        """Look up if we have already persisted an event for the transaction ID,
-        returning the event ID if so.
-        """
-        return await self.db_pool.simple_select_one_onecol(
-            table="event_txn_id",
-            keyvalues={
-                "room_id": room_id,
-                "user_id": user_id,
-                "token_id": token_id,
-                "txn_id": txn_id,
-            },
-            retcol="event_id",
-            allow_none=True,
-            desc="get_event_id_from_transaction_id_and_token_id",
-        )
-
     async def get_event_id_from_transaction_id_and_device_id(
         self, room_id: str, user_id: str, device_id: str, txn_id: str
     ) -> Optional[str]:
@@ -2072,29 +2053,35 @@ class EventsWorkerStore(SQLBaseStore):
         """
 
         mapping = {}
-        txn_id_to_event: Dict[Tuple[str, int, str], str] = {}
+        txn_id_to_event: Dict[Tuple[str, str, str, str], str] = {}
 
         for event in events:
-            token_id = getattr(event.internal_metadata, "token_id", None)
+            device_id = getattr(event.internal_metadata, "device_id", None)
             txn_id = getattr(event.internal_metadata, "txn_id", None)
 
-            if token_id and txn_id:
+            if device_id and txn_id:
                 # Check if this is a duplicate of an event in the given events.
-                existing = txn_id_to_event.get((event.room_id, token_id, txn_id))
+                existing = txn_id_to_event.get(
+                    (event.room_id, event.sender, device_id, txn_id)
+                )
                 if existing:
                     mapping[event.event_id] = existing
                     continue
 
                 # Check if this is a duplicate of an event we've already
                 # persisted.
-                existing = await self.get_event_id_from_transaction_id_and_token_id(
-                    event.room_id, event.sender, token_id, txn_id
+                existing = await self.get_event_id_from_transaction_id_and_device_id(
+                    event.room_id, event.sender, device_id, txn_id
                 )
                 if existing:
                     mapping[event.event_id] = existing
-                    txn_id_to_event[(event.room_id, token_id, txn_id)] = existing
+                    txn_id_to_event[
+                        (event.room_id, event.sender, device_id, txn_id)
+                    ] = existing
                 else:
-                    txn_id_to_event[(event.room_id, token_id, txn_id)] = event.event_id
+                    txn_id_to_event[
+                        (event.room_id, event.sender, device_id, txn_id)
+                    ] = event.event_id
 
         return mapping
 
diff --git a/synapse/storage/schema/__init__.py b/synapse/storage/schema/__init__.py
index 649d3c8e9f..422f11f59e 100644
--- a/synapse/storage/schema/__init__.py
+++ b/synapse/storage/schema/__init__.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-SCHEMA_VERSION = 80  # remember to update the list below when updating
+SCHEMA_VERSION = 81  # remember to update the list below when updating
 """Represents the expectations made by the codebase about the database schema
 
 This should be incremented whenever the codebase changes its requirements on the
@@ -114,19 +114,15 @@ Changes in SCHEMA_VERSION = 79
 Changes in SCHEMA_VERSION = 80
     - The event_txn_id_device_id is always written to for new events.
     - Add tables for the task scheduler.
+
+Changes in SCHEMA_VERSION = 81
+    - The event_txn_id is no longer written to for new events.
 """
 
 
 SCHEMA_COMPAT_VERSION = (
-    # Queries against `event_stream_ordering` columns in membership tables must
-    # be disambiguated.
-    #
-    # The threads_id column must written to with non-null values for the
-    # event_push_actions, event_push_actions_staging, and event_push_summary tables.
-    #
-    # insertions to the column `full_user_id` of tables profiles and user_filters can no
-    # longer be null
-    76
+    # The `event_txn_id_device_id` must be written to for new events.
+    80
 )
 """Limit on how far the synapse codebase can be rolled back without breaking db compat
 
diff --git a/tests/handlers/test_message.py b/tests/handlers/test_message.py
index 9691d66b48..1c5897c84e 100644
--- a/tests/handlers/test_message.py
+++ b/tests/handlers/test_message.py
@@ -46,18 +46,11 @@ class EventCreationTestCase(unittest.HomeserverTestCase):
         self._persist_event_storage_controller = persistence
 
         self.user_id = self.register_user("tester", "foobar")
-        self.access_token = self.login("tester", "foobar")
-        self.room_id = self.helper.create_room_as(self.user_id, tok=self.access_token)
-
-        info = self.get_success(
-            self.hs.get_datastores().main.get_user_by_access_token(
-                self.access_token,
-            )
-        )
-        assert info is not None
-        self.token_id = info.token_id
+        device_id = "dev-1"
+        access_token = self.login("tester", "foobar", device_id=device_id)
+        self.room_id = self.helper.create_room_as(self.user_id, tok=access_token)
 
-        self.requester = create_requester(self.user_id, access_token_id=self.token_id)
+        self.requester = create_requester(self.user_id, device_id=device_id)
 
     def _create_and_persist_member_event(self) -> Tuple[EventBase, EventContext]:
         # Create a member event we can use as an auth_event