During a query compilation process, a query is received that is directed to a set of source tables, each source table from the set of source tables being organized into at least one micro-partition and the query including at least one pruning operation. During the query compilation process, a modification of the query is performed for adjusting the at least one pruning operation, the modification being based on a set of statistics collected for previous pruning operations on at least a portion of the set of source tables and a set of heuristics, the set of statistics indicating at least an amount of execution time for each previous query associated with each of the previous pruning operations. The query is compiled including the modification of the query. The compiled query is provided to an execution node of a database system for execution.