[Experiment] Use incremental vacuum to speed up delete? (#2800)

* DB: Use incremental vacuum

* Chore: Add log for delete monitor exec. time

* WIP: Test synchronous NORMAL

server/server.js

@@ -902,6 +902,8 @@ let needSetup = false;
                     delete server.monitorList[monitorID];
                 }
 
+                const startTime = Date.now();
+
                 await R.exec("DELETE FROM monitor WHERE id = ? AND user_id = ? ", [
                     monitorID,
                     socket.userID,
@@ -910,6 +912,10 @@ let needSetup = false;
                 // Fix #2880
                 apicache.clear();
 
+                const endTime = Date.now();
+
+                log.info("DB", `Delete Monitor completed in : ${endTime - startTime} ms`);
+
                 callback({
                     ok: true,
                     msg: "Deleted Successfully.",