1. A system for processing a query request, comprising: a local database storing metadata and local data, wherein the local database stores a local database query processing layer configured to process a local sub-query to a local database; an external database storing external data and configured to return external data in response to an external sub-query to an external database; a memory configured to store the metadata retrieved from the local database; and an application server comprising a processor, wherein the processor is configured to fulfill the query request by retrieving the metadata stored in the local database, ascertaining at least one sub-query associated with a first data source location type, initiating the at least one sub-query comprising a local query request to the local database in response to ascertaining that the first data source location type is a local data type, initiating the at least one sub-query comprising the external query request to the external database in response to ascertaining that the first data source location type is an external data type, and analyzing a query tree data structure comprising one or more nodes representing one or more sub-queries required to be performed in order to generate a query result.
1. A system for processing a query request, comprising: a local database storing metadata and local data, wherein the local database stores a local database query processing layer configured to process a local sub-query to a local database; an external database storing external data and configured to return external data in response to an external sub-query to an external database; a memory configured to store the metadata retrieved from the local database; and an application server comprising a processor, wherein the processor is configured to fulfill the query request by retrieving the metadata stored in the local database, ascertaining at least one sub-query associated with a first data source location type, initiating the at least one sub-query comprising a local query request to the local database in response to ascertaining that the first data source location type is a local data type, initiating the at least one sub-query comprising the external query request to the external database in response to ascertaining that the first data source location type is an external data type, and analyzing a query tree data structure comprising one or more nodes representing one or more sub-queries required to be performed in order to generate a query result. 2. The system of claim 1 wherein the processor is further configured to determine that a sub-query associated with each respective one or more nodes in the query tree has been initiated.