regclass

regclass is a data type in PostgreSQL that stores the OID (Object Identifier) of a relation, such as a table, view, or sequence. When you use regclass, you are essentially referencing a specific database object by its unique OID. This is useful for functions or table columns that need to refer to other database objects without hardcoding their names. For instance, a function might accept a regclass argument to specify which table it should operate on. The system automatically resolves the regclass value to the actual relation's OID, ensuring that even if the relation is renamed, the reference remains valid as long as the OID is preserved.

When you insert a table name into a regclass column or pass it as an argument to a function expecting regclass, PostgreSQL converts the provided text representation of the table name into its corresponding OID. This conversion happens at parse time. If the table name is ambiguous or does not exist, an error will be raised. The regclass type provides a robust way to manage relationships between database objects programmatically. It is generally preferred over using simple text strings for referencing objects because it offers type safety and handles internal object identification more reliably.