Abstract: Techniques are provided for determining costs for alternative execution plans for a query, where at least a portion of the data items required by the query are in in-memory compression-units within volatile memory. The techniques involve maintaining in-memory statistics, such as statistics that indicate what fraction of a table is currently present in in-memory compression units, and the cost of decompressing in-memory compression units. Those statistics are used to determine, for example, the cost of a table scan that retrieves some or all of the necessary data items from the in-memory compression-units.

Abstract: Techniques are provided for determining costs for alternative execution plans for a query, where at least a portion of the data items required by the query are in in-memory compression-units within volatile memory. The techniques involve maintaining in-memory statistics, such as statistics that indicate what fraction of a table is currently present in in-memory compression units, and the cost of decompressing in-memory compression units. Those statistics are used to determine, for example, the cost of a table scan that retrieves some or all of the necessary data items from the in-memory compression-units.

Abstract: A method, non-transitory computer readable medium, and apparatus for receiving data from a cloud database. One or more queries requesting data from the cloud database are received. The one or more queries are converted from a row-store database query into a column-store database query. An optimal join plan is identified for the one or more queries using a cost based optimizer based on metadata for one or more relations in the cloud database. The optimal join plan is executed using a cloud application programming interface.

Abstract: Computer-implemented methods, systems and computer-readable media for providing a query layer for cloud databases comprise importing data into said cloud by at least one of the computing devices, converting at least one of the queries over row-store database into a query over column-store database by means of cost based query optimizer and retrieving said data from the column-store database based on said query by at least one of the computing devices.