db.Mux.RLock()
	if stmt, ok := db.Stmts[query]; ok && (!stmt.Transaction || isTransaction) {
		db.Mux.RUnlock()
		// wait for other goroutines prepared
		<-stmt.prepared
		if stmt.prepareErr != nil {
			return Stmt{}, stmt.prepareErr
		}

		return *stmt, nil
	}
	db.Mux.RUnlock()

	db.Mux.Lock()
	// double check

	}

	pdb.Mux.Lock()
	if len(pdb.Stmts) == 0 {
		pdb.Mux.Unlock()
		t.Fatalf("prepared stmt can not be empty")
	}
	pdb.Mux.Unlock()

	pdb.Reset()
	pdb.Mux.Lock()
	defer pdb.Mux.Unlock()
	if len(pdb.Stmts) != 0 {
		t.Fatalf("prepared stmt should be empty")
	}