feat: Add timestamp to msgs_index7 to employ it in calc_sort_timestamp()

Tested on some random chat, the SQL query took 1.411202ms (vs 6.692714ms before) in median. Still
looks a bit slow, but already better.

src/chat.rs

@@ -1227,20 +1227,19 @@ impl ChatId {
             // NB: Received outgoing messages may break sorting of fresh incoming ones, but this
             // shouldn't happen frequently. Seen incoming messages don't really break sorting of
             // fresh ones, they rather mean that older incoming messages are actually seen as well.
+            let states = match incoming {
+                true => "13, 16, 18, 20, 24, 26", // `> MessageState::InFresh`
+                false => "18, 20, 24, 26",        // `> MessageState::InSeen`
+            };
             context
                 .sql
                 .query_row_optional(
-                    "SELECT MAX(timestamp)
-                     FROM msgs
-                     WHERE chat_id=? AND hidden=0 AND state>?
-                     HAVING COUNT(*) > 0",
-                    (
-                        self,
-                        match incoming {
-                            true => MessageState::InFresh,
-                            false => MessageState::InSeen,
-                        },
+                    &format!(
+                        "SELECT MAX(timestamp) FROM msgs
+                        WHERE state IN ({states}) AND hidden=0 AND chat_id=?
+                        HAVING COUNT(*) > 0"
                     ),
+                    (self,),
                     |row| {
                         let ts: i64 = row.get(0)?;
                         Ok(ts)

src/message.rs

@@ -1366,7 +1366,7 @@ pub enum MessageState {
     OutDelivered = 26,
 
     /// Outgoing message read by the recipient (two checkmarks; this
-    /// requires goodwill on the receiver's side). Not used in the db for new messages.
+    /// requires goodwill on the receiver's side). API-only, not used in the db.
     OutMdnRcvd = 28,
 }
 

src/sql/migrations.rs

@@ -1271,6 +1271,18 @@ CREATE INDEX gossip_timestamp_index ON gossip_timestamp (chat_id, fingerprint);
         .await?;
     }
 
+    inc_and_check(&mut migration_version, 135)?;
+    if dbversion < migration_version {
+        // Tweak the index for `chat::calc_sort_timestamp()`.
+        sql.execute_migration(
+            "UPDATE msgs SET state=26 WHERE state=28;
+            DROP INDEX IF EXISTS msgs_index7;
+            CREATE INDEX msgs_index7 ON msgs (state, hidden, chat_id, timestamp);",
+            migration_version,
+        )
+        .await?;
+    }
+
     let new_version = sql
         .get_raw_config_int(VERSION_CFG)
         .await?

src/tests/verified_chats.rs

@@ -277,7 +277,7 @@ async fn test_old_message_5() -> Result<()> {
     .await?
     .unwrap();
 
-    assert!(msg_sent.sort_timestamp == msg_incoming.sort_timestamp);
+    assert_eq!(msg_sent.sort_timestamp, msg_incoming.sort_timestamp);
     alice
         .golden_test_chat(msg_sent.chat_id, "test_old_message_5")
         .await;