From 1259832491dc3e31a41baf16b48e4783367d6d1f Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 27 Jun 2022 14:07:35 +0100
Subject: [PATCH 1/6] Improve performance of getting unread counts in rooms

---
 synapse/storage/databases/main/__init__.py          |  2 +-
 .../storage/databases/main/event_push_actions.py    | 13 ++++++++++++-
 tests/storage/test_event_push_actions.py            |  2 ++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/synapse/storage/databases/main/__init__.py b/synapse/storage/databases/main/__init__.py
index 57aaf778ec2a..a3d31d373724 100644
--- a/synapse/storage/databases/main/__init__.py
+++ b/synapse/storage/databases/main/__init__.py
@@ -87,7 +87,6 @@ class DataStore(
     RoomStore,
     RoomBatchStore,
     RegistrationStore,
-    StreamWorkerStore,
     ProfileStore,
     PresenceStore,
     TransactionWorkerStore,
@@ -112,6 +111,7 @@ class DataStore(
     SearchStore,
     TagsStore,
     AccountDataStore,
+    StreamWorkerStore,
     OpenIdStore,
     ClientIpWorkerStore,
     DeviceStore,
diff --git a/synapse/storage/databases/main/event_push_actions.py b/synapse/storage/databases/main/event_push_actions.py
index 10a7962382f7..d0916e7874b9 100644
--- a/synapse/storage/databases/main/event_push_actions.py
+++ b/synapse/storage/databases/main/event_push_actions.py
@@ -27,6 +27,7 @@
 )
 from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.databases.main.receipts import ReceiptsWorkerStore
+from synapse.storage.databases.main.stream import StreamWorkerStore
 from synapse.util import json_encoder
 from synapse.util.caches.descriptors import cached
 
@@ -122,7 +123,7 @@ def _deserialize_action(actions: str, is_highlight: bool) -> List[Union[dict, st
         return DEFAULT_NOTIF_ACTION
 
 
-class EventPushActionsWorkerStore(ReceiptsWorkerStore, EventsWorkerStore, SQLBaseStore):
+class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBaseStore):
     def __init__(
         self,
         database: DatabasePool,
@@ -291,12 +292,22 @@ def _get_notif_unread_count_for_user_room(
         actions that have been deleted from `event_push_actions` table.
         """
 
+        # If there have been no events in the room since the stream ordering,
+        # there can't be any push actions either.
+        if not self._events_stream_cache.has_entity_changed(room_id, stream_ordering):
+            return 0, 0
+
         clause = ""
         args = [user_id, room_id, stream_ordering]
         if max_stream_ordering is not None:
             clause = "AND ea.stream_ordering <= ?"
             args.append(max_stream_ordering)
 
+            # If the max stream ordering is less than the min stream ordering,
+            # then obviously there are zero push actions in that range.
+            if max_stream_ordering < stream_ordering:
+                return 0, 0
+
         sql = f"""
             SELECT
                COUNT(CASE WHEN notif = 1 THEN 1 END),
diff --git a/tests/storage/test_event_push_actions.py b/tests/storage/test_event_push_actions.py
index 2ac5f6db5e74..e13401c44b41 100644
--- a/tests/storage/test_event_push_actions.py
+++ b/tests/storage/test_event_push_actions.py
@@ -86,6 +86,8 @@ def _inject_actions(stream: int, action: list) -> None:
             event.internal_metadata.is_outlier.return_value = False
             event.depth = stream
 
+            self.store._events_stream_cache.entity_has_changed(room_id, stream)
+
             self.get_success(
                 self.store.add_push_actions_to_staging(
                     event.event_id,

From ad94c6b629edd8cd3a31b0b386f7496bf53f3ce2 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 27 Jun 2022 14:08:37 +0100
Subject: [PATCH 2/6] Newsfile

---
 changelog.d/13119.misc | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/13119.misc

diff --git a/changelog.d/13119.misc b/changelog.d/13119.misc
new file mode 100644
index 000000000000..3bb51962e79e
--- /dev/null
+++ b/changelog.d/13119.misc
@@ -0,0 +1 @@
+Reduce DB usage of `/sync` when a large number of unread messages have recently been sent in a room.

From 8845dfdeaa43ddade14759a17dde8dffa5bcf0cc Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 27 Jun 2022 14:28:17 +0100
Subject: [PATCH 3/6] Fix lint

---
 .../databases/main/event_push_actions.py      |  3 +-
 synapse/storage/databases/main/stream.py      | 28 +++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/synapse/storage/databases/main/event_push_actions.py b/synapse/storage/databases/main/event_push_actions.py
index d0916e7874b9..9bdfa2d091b9 100644
--- a/synapse/storage/databases/main/event_push_actions.py
+++ b/synapse/storage/databases/main/event_push_actions.py
@@ -25,7 +25,6 @@
     LoggingDatabaseConnection,
     LoggingTransaction,
 )
-from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.databases.main.receipts import ReceiptsWorkerStore
 from synapse.storage.databases.main.stream import StreamWorkerStore
 from synapse.util import json_encoder
@@ -219,7 +218,7 @@ def _get_unread_counts_by_receipt_txn(
                 retcol="event_id",
             )
 
-            stream_ordering = self.get_stream_id_for_event_txn(txn, event_id)  # type: ignore[attr-defined]
+            stream_ordering = self.get_stream_id_for_event_txn(txn, event_id)
 
         return self._get_unread_counts_by_pos_txn(
             txn, room_id, user_id, stream_ordering
diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py
index 8e88784d3ce3..f5fd6f389956 100644
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -46,10 +46,12 @@
     Set,
     Tuple,
     cast,
+    overload,
 )
 
 import attr
 from frozendict import frozendict
+from typing_extensions import Literal
 
 from twisted.internet import defer
 
@@ -795,6 +797,32 @@ async def get_current_room_stream_token_for_room_id(
         )
         return RoomStreamToken(topo, stream_ordering)
 
+    @overload
+    def get_stream_id_for_event_txn(
+        self,
+        txn: LoggingTransaction,
+        event_id: str,
+        allow_none: Literal[True],
+    ) -> int:
+        ...
+
+    @overload
+    def get_stream_id_for_event_txn(
+        self,
+        txn: LoggingTransaction,
+        event_id: str,
+    ) -> int:
+        ...
+
+    @overload
+    def get_stream_id_for_event_txn(
+        self,
+        txn: LoggingTransaction,
+        event_id: str,
+        allow_none: bool = False,
+    ) -> Optional[int]:
+        ...
+
     def get_stream_id_for_event_txn(
         self,
         txn: LoggingTransaction,

From 818463fa1c3e115bdfae8b63456888fc15eefd2a Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 27 Jun 2022 15:40:36 +0100
Subject: [PATCH 4/6] Fix port DB script

---
 synapse/_scripts/synapse_port_db.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/synapse/_scripts/synapse_port_db.py b/synapse/_scripts/synapse_port_db.py
index 9c06c837dc1d..f3f9c6d54c7b 100755
--- a/synapse/_scripts/synapse_port_db.py
+++ b/synapse/_scripts/synapse_port_db.py
@@ -270,6 +270,9 @@ def get_reactor(self) -> ISynapseReactor:
     def get_instance_name(self) -> str:
         return "master"
 
+    def should_send_federation(self) -> bool:
+        return False
+
 
 class Porter:
     def __init__(

From 5e4f5dbd95521e7e7ebc85cbdeb82cd54096d658 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 29 Jun 2022 11:01:00 +0100
Subject: [PATCH 5/6] Update
 synapse/storage/databases/main/event_push_actions.py

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>
---
 synapse/storage/databases/main/event_push_actions.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/synapse/storage/databases/main/event_push_actions.py b/synapse/storage/databases/main/event_push_actions.py
index 9bdfa2d091b9..747c6560ec70 100644
--- a/synapse/storage/databases/main/event_push_actions.py
+++ b/synapse/storage/databases/main/event_push_actions.py
@@ -304,7 +304,7 @@ def _get_notif_unread_count_for_user_room(
 
             # If the max stream ordering is less than the min stream ordering,
             # then obviously there are zero push actions in that range.
-            if max_stream_ordering < stream_ordering:
+            if max_stream_ordering <= stream_ordering:
                 return 0, 0
 
         sql = f"""

From cf10193a805607f5ef51466a1c6ba9e700b9cb42 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 29 Jun 2022 11:03:01 +0100
Subject: [PATCH 6/6] Fix typing

---
 synapse/storage/databases/main/stream.py | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py
index f5fd6f389956..3a1df7776c90 100644
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -802,15 +802,7 @@ def get_stream_id_for_event_txn(
         self,
         txn: LoggingTransaction,
         event_id: str,
-        allow_none: Literal[True],
-    ) -> int:
-        ...
-
-    @overload
-    def get_stream_id_for_event_txn(
-        self,
-        txn: LoggingTransaction,
-        event_id: str,
+        allow_none: Literal[False] = False,
     ) -> int:
         ...