In some examples, a database system identifies a plurality of query portions in a database query that contain references to a first external table, the first external table being based on data from a remote data store coupled to the database system over a network. The database system creates a common spool portion that includes projections and selections of the plurality of query portions, and rewrites the plurality of query portions into rewritten query portions that refer to a spool containing an output of the common spool portion. For execution of the database query, the database system determines, as part of optimizer planning, whether to use the plurality of query portions or the common spool portion and the rewritten query portions.