Fix get_constraints to do multi-column indexes properly on pg

            constraints[constraint]['columns'].add(column)

        # Now get indexes

        cursor.execute("""

            SELECT c2.relname, attr.attname, idx.indkey, idx.indisunique, idx.indisprimary

            SELECT

                c2.relname,

                ARRAY(

                    SELECT attr.attname

                    FROM unnest(idx.indkey) i, pg_catalog.pg_attribute attr

                    WHERE

                        attr.attnum = i AND

                        attr.attrelid = c.oid

                ),

                idx.indisunique,

                idx.indisprimary

            FROM pg_catalog.pg_class c, pg_catalog.pg_class c2,

                pg_catalog.pg_index idx, pg_catalog.pg_attribute attr

                pg_catalog.pg_index idx

            WHERE c.oid = idx.indrelid

                AND idx.indexrelid = c2.oid

                AND attr.attrelid = c.oid

                AND attr.attnum = idx.indkey[0]

                AND c.relname = %s

        """, [table_name])

        for index, column, coli, unique, primary in cursor.fetchall():

            # If we're the first column, make the record

        for index, columns, unique, primary in cursor.fetchall():

            if index not in constraints:

                constraints[index] = {

                    "columns": set(),

                    "primary_key": False,

                    "unique": False,

                    "columns": set(columns),

                    "primary_key": primary,

                    "unique": unique,

                    "foreign_key": False,

                    "check": False,

                    "index": True,

                }

            # Record the details

            constraints[index]['columns'].add(column)

        return constraints