func updateHandler(ctx *fasthttp.RequestCtx) {
	n := common.GetQueriesCount(ctx)

	worlds := make([]common.World, n)
	for i := 0; i < n; i++ {
		w := &worlds[i]
		fetchRandomWorld(w)
		w.RandomNumber = int32(common.RandomWorldNum())
	}

	// sorting is required for insert deadlock prevention.
	sort.Sort(common.WorldsByID(worlds))
	txn, err := db.Begin()
	if err != nil {
		log.Fatalf("Error starting transaction: %s", err)
	}

	for i := 0; i < n; i++ {
		w := &worlds[i]
		if _, err = txn.Exec("worldUpdateStmt", w.RandomNumber, w.Id); err != nil {
			log.Fatalf("Error updating world row %d: %s", i, err)
		}
	}
	if err = txn.Commit(); err != nil {
		log.Fatalf("Error when commiting world rows: %s", err)
	}

	common.JSONMarshal(ctx, worlds)
}
func queriesHandler(ctx *fasthttp.RequestCtx) {
	n := common.GetQueriesCount(ctx)
	worlds := make([]common.World, n)
	for i := 0; i < n; i++ {
		fetchRandomWorld(&worlds[i])
	}
	common.JSONMarshal(ctx, worlds)
}
func dbHandler(ctx *fasthttp.RequestCtx) {
	var w common.World
	fetchRandomWorld(&w)
	common.JSONMarshal(ctx, &w)
}