From 7d261ff067fc755ce38e62bdfba2fb555febac65 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Tue, 19 Jul 2022 10:45:22 +0100
Subject: [PATCH 1/2] Intern state key

---
 synapse/storage/databases/state/bg_updates.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/synapse/storage/databases/state/bg_updates.py b/synapse/storage/databases/state/bg_updates.py
index fa9eadaca7ea..a7fcc564a992 100644
--- a/synapse/storage/databases/state/bg_updates.py
+++ b/synapse/storage/databases/state/bg_updates.py
@@ -24,6 +24,7 @@
 from synapse.storage.engines import PostgresEngine
 from synapse.storage.state import StateFilter
 from synapse.types import MutableStateMap, StateMap
+from synapse.util.caches import intern_string
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -136,7 +137,7 @@ def _get_state_groups_from_groups_txn(
                 txn.execute(sql % (where_clause,), args)
                 for row in txn:
                     typ, state_key, event_id = row
-                    key = (typ, state_key)
+                    key = (intern_string(typ), intern_string(state_key))
                     results[group][key] = event_id
         else:
             max_entries_returned = state_filter.max_entries_returned()

From 92cad4a4f6389637f5411bee8f94d4ef8a192262 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Tue, 19 Jul 2022 12:42:14 +0100
Subject: [PATCH 2/2] Newsfile

---
 changelog.d/13323.misc | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/13323.misc

diff --git a/changelog.d/13323.misc b/changelog.d/13323.misc
new file mode 100644
index 000000000000..3caa94a2f66c
--- /dev/null
+++ b/changelog.d/13323.misc
@@ -0,0 +1 @@
+Reduce memory usage of state caches.