// generate a random bucket name.
	bucketName := getRandomBucketName()
	// content of the object to be uploaded.
	buffer1 := bytes.NewReader([]byte("hello world"))

	// preparing for upload by generating the upload URL.
	objectName := "test-object"
	request, err := newTestSignedRequest(http.MethodPut, getPutObjectURL(s.endPoint, bucketName, objectName),

		db.Mux.Unlock()
		// wait for other goroutines prepared
		<-stmt.prepared
		if stmt.prepareErr != nil {
			return Stmt{}, stmt.prepareErr
		}

		return *stmt, nil
	}

	// cache preparing stmt first
	cacheStmt := Stmt{Transaction: isTransaction, prepared: make(chan struct{})}
	db.Stmts[query] = &cacheStmt
	db.Mux.Unlock()

	// prepare completed
	defer close(cacheStmt.prepared)