> Theoretically postgres already has a robust layer of security and validation; although it may not be used for the typical web app.
What Postgres has in terms of validation is essentially a not terribly sophisticated type system, plus stored procedures in PL/pgSQL, Perl, Python or Tcl. These are frankly a pain to manage. In terms of security, well... outside of stored procedures, there is no special way of restricting a given connection/user to only rows with the right foreign key in a table. On the other hand, many web framework have some sort of authorization framework.
What Postgres has in terms of validation is essentially a not terribly sophisticated type system, plus stored procedures in PL/pgSQL, Perl, Python or Tcl. These are frankly a pain to manage. In terms of security, well... outside of stored procedures, there is no special way of restricting a given connection/user to only rows with the right foreign key in a table. On the other hand, many web framework have some sort of authorization framework.