How do I get the primary key(s) of a table from Postgres via plpgsql?

Question

Given a table name, how do I extract a list of primary key columns and their datatypes from a plpgsql function?

Answer 1

Take a look at pg_constraint system table. Or information_schema.table_constraints view if you prefer stick close to the SQL standard.

For a complete example connect to a DB using psql with the "-E" option and type \d <some_table> - you'll see the actual queries used in describing a table.