Add index on message timestamps

database/upgrades/00-latest-revision.sql

@@ -1,4 +1,4 @@
--- v0 -> v56 (compatible with v45+): Latest revision
+-- v0 -> v57 (compatible with v45+): Latest revision
 
 CREATE TABLE "user" (
     mxid     TEXT PRIMARY KEY,
@@ -82,6 +82,8 @@ CREATE TABLE message (
     FOREIGN KEY (chat_jid, chat_receiver) REFERENCES portal(jid, receiver) ON DELETE CASCADE
 );
 
+CREATE INDEX message_timestamp_idx ON message (chat_jid, chat_receiver, timestamp);
+
 CREATE TABLE poll_option_id (
     msg_mxid TEXT,
     opt_id   TEXT,

database/upgrades/57-message-timestamp-index.sql

@@ -0,0 +1,2 @@
+-- v57 (compatible with v45+): Add index for message timestamp to make read receipt handling faster
+CREATE INDEX message_timestamp_idx ON message (chat_jid, chat_receiver, timestamp);