Stored procedures and functions are implementing the business logic of the database. When migrating the SQL Server database to PostgreSQL, you will need to convert stored procedures and functions properly, paying attention to parameter handling, rowset retrieval, and other specific syntax constructions. 

SQL Server uses a dialect of SQL called Transact-SQL (or T-SQL) for stored procedures and functions, while PostgreSQL uses Procedural Language/PostgreSQL (or PL/pgSQL) for the same. These languages have significantly different syntax and capabilities, so stored procedures and functions must be carefully analyzed and converted.