Abstract: Cloud computing is a promising computing model that provides a combination of parallel and distributed computing paradigms. It has the characteristics of on demand provisioning of a shared pool of configurable computing resources as a service. It provides a cost effective paradigm of computational, storage and database resources to users over the internet. Cloud storage is an important service that is provided by the cloud system, it provides the data owners with high accessibility, availability and scalability in respect to increasing the amount of their data in cloud repositories. The increasing number of users query data from deployed virtual instances can lead to increased loads on the cloud data management system. Multiple queries compete for hardware resources causing resources contention within a rapidly changing in environment computational properties. So efficient concurrent queries execution on especially structured data in such environment has become an important challenge.