core: optimize member subscriptions query

src/Simplex/Chat/Store/Connections.hs

@@ -271,31 +271,34 @@ getUCLConnsToSub db User {userId} filterToSubscribe =
     cond = " AND c.conn_status != ?"
 
 getMemberConnsToSub :: DB.Connection -> User -> Bool -> IO [ConnId]
-getMemberConnsToSub db User {userId, userContactId} filterToSubscribe =
-  map fromOnly <$>
-    DB.query
-      db
-      query
-      ((userId, ConnDeleted, userContactId)
-        :. (GSMemRemoved, GSMemLeft, GSMemGroupDeleted, GSMemRemoved, GSMemLeft, GSMemGroupDeleted))
+getMemberConnsToSub db User {userId, userContactId} filterToSubscribe = do
+  DB.execute
+    db
+    [sql|
+      CREATE TABLE temp_user_groups AS
+      SELECT g.group_id
+      FROM groups g
+      JOIN group_members mu ON mu.group_id = g.group_id
+      WHERE g.user_id = ?
+        AND mu.contact_id = ?
+        AND mu.member_status NOT IN (?,?,?);
+    |]
+    (userId, userContactId, GSMemRemoved, GSMemLeft, GSMemGroupDeleted)
+  connIds <- map fromOnly <$> DB.query db query (GSMemRemoved, GSMemLeft, GSMemGroupDeleted, ConnDeleted)
+  DB.execute_ db "DROP TABLE temp_user_groups"
+  pure connIds
   where
     query
-      | filterToSubscribe = baseQuery <> " AND c.to_subscribe = 1 " <> cond
-      | otherwise = baseQuery <> " " <> cond
+      | filterToSubscribe = baseQuery <> " AND c.to_subscribe = 1"
+      | otherwise = baseQuery
     baseQuery =
       [sql|
         SELECT c.agent_conn_id
-        FROM connections c
-        JOIN group_members m ON m.group_member_id = c.group_member_id
-        JOIN groups g ON g.group_id = m.group_id
-        JOIN group_members mu ON mu.group_id = g.group_id
-        WHERE c.user_id = ?
-      |]
-    cond =
-      [sql|
-        AND c.conn_status != ?
-        AND mu.contact_id = ? AND mu.member_status NOT IN (?,?,?)
-        AND m.member_status NOT IN (?,?,?)
+        FROM temp_user_groups ug
+        JOIN group_members m ON m.group_id = ug.group_id
+        JOIN connections c ON c.group_member_id = m.group_member_id
+        WHERE m.member_status NOT IN (?,?,?)
+          AND c.conn_status != ?
       |]
 
 getPendingConnsToSub :: DB.Connection -> User -> Bool -> IO [ConnId]