From bc5dc69d8d7b004d4062d53a912be11b229e1c57 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 15 Apr 2024 12:13:53 +0100
Subject: [PATCH 1/2] Fix remote receipts for events we don't have

Introduced in #17032
---
 synapse/storage/databases/main/receipts.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/synapse/storage/databases/main/receipts.py b/synapse/storage/databases/main/receipts.py
index 9660fc46997..13387a38396 100644
--- a/synapse/storage/databases/main/receipts.py
+++ b/synapse/storage/databases/main/receipts.py
@@ -734,9 +734,13 @@ def _insert_linearized_receipt_txn(
                 thread_clause = "r.thread_id = ?"
                 thread_args = (thread_id,)
 
+            # If the receipt doesn't have a stream ordering it is because we
+            # don't have the associated event, and so must be a remote receipt.
+            # Hence it's safe to just allow new receipts to clobber it.
             sql = f"""
             SELECT r.event_stream_ordering, r.event_id FROM receipts_linearized AS r
-            WHERE r.room_id = ? AND r.receipt_type = ? AND r.user_id = ? AND {thread_clause}
+            WHERE r.room_id = ? AND r.receipt_type = ? AND r.user_id = ?
+            AND r.event_stream_ordering IS NOT NULL AND {thread_clause}
             """
             txn.execute(
                 sql,

From 5104594a86b4c2058839618ae5fc3b7cb1a451a7 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Mon, 15 Apr 2024 12:14:41 +0100
Subject: [PATCH 2/2] Newsfile

---
 changelog.d/17096.misc | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/17096.misc

diff --git a/changelog.d/17096.misc b/changelog.d/17096.misc
new file mode 100644
index 00000000000..b03f6f42e5f
--- /dev/null
+++ b/changelog.d/17096.misc
@@ -0,0 +1 @@
+Use new receipts column to optimise receipt and push action SQL queries. Contributed by Nick @ Beeper (@fizzadar).