A database system is operable to determine a plurality of queries for execution. Query data for each query of the plurality of queries is determined, where the query data for the each query indicates a memory usage estimate, an internal runtime estimate, and an external runtime estimate. Query initiation data is generated by determining whether to initiate execution of one query of the plurality of queries at a first temporal period occurring after initiating execution of a subset of the plurality of queries and occurs before the execution of the subset of the plurality of queries is complete, based on the query data of the one query. Execution of the one query is initiated when the query initiation data indicates a determination to initiate execution of the one query in the first temporal period.