Filters a database schema's relations, keeping only the given relations, and those considered ancestors via foreign key references. Foreign key references involving removed relations are also removed.
# S3 method for database_schema
reduce(x, main, ...)A database schema, with the auxiliary relations and foreign key references removed.
A database schema, whose relations are to be filtered.
A character vector, containing names of relations to be considered as the "main" relations.
further arguments passed to or from other methods.
This method takes a given set of main relations, rather than inferring them.
Using rejoin on the database resulting from decomposing a data
frame with the reduced schema is likely to fail or return incomplete results.