Hard Parse
The expensive Oracle parse path that must create a new executable cursor, including syntax, semantic, privilege, optimization, and library-cache work.
Oracle Runtime Context
A hard parse creates a new executable cursor and can involve syntax and semantic checks, privilege validation, optimization, and library-cache work. High hard-parse rates therefore consume CPU and shared-pool resources, often because applications generate literal SQL or fail to reuse cursors.
Parse Boundary
Not every parse call is a hard parse. A soft parse can locate and reuse a compatible shared cursor, although even soft parsing still has nonzero lookup and validation cost.