Get the column metadata

SELECT
    col.attname as column_name,
    (
        SELECT
            pg_catalog.pg_get_expr(def.adbin, def.adrelid)
        FROM
            pg_catalog.pg_attrdef def
        WHERE
                def.adrelid = col.attrelid
            AND def.adnum = col.attnum
            AND col.atthasdef
    ) as column_default,
    col.attnum as ordinal_position,
    CASE
        WHEN typ.typcategory ='E'
        THEN
            'enum'
        WHEN typ.typcategory='C'
        THEN
            'composite'

    ELSE
        pg_catalog.format_type(col.atttypid, col.atttypmod)
    END
    AS type_format,
    (
        SELECT
            pg_get_serial_sequence(format('%I.%I',tabsch.nspname,tab.relname), col.attname) IS NOT NULL
        FROM
            pg_catalog.pg_class tab
            INNER JOIN pg_catalog.pg_namespace tabsch
            ON  tab.relnamespace=tabsch.oid
        WHERE
            tab.oid=col.attrelid
    ) as col_serial,



    typ.typcategory as type_category,
    CASE
        WHEN typ.typcategory='E'
        THEN
        (
            SELECT
                string_agg(quote_literal(enumlabel),',')
            FROM
                pg_catalog.pg_enum enm
            WHERE enm.enumtypid=typ.oid
        )
        WHEN typ.typcategory='C'
        THEN
        (
            SELECT
                string_agg(
                    format('%I %s',
                        attname,
                        pg_catalog.format_type(atttypid, atttypmod)
                    )
                ,
                ','
                )
            FROM
                pg_catalog.pg_attribute
            WHERE
                attrelid=format(
                    '%I.%I',
                    sch.nspname,
                    typ.typname)::regclass
                )
    END AS typ_elements,
    col.attnotnull as not_null
FROM
    pg_catalog.pg_attribute col
    INNER JOIN pg_catalog.pg_type typ
        ON  col.atttypid=typ.oid
    INNER JOIN pg_catalog.pg_namespace sch
        ON typ.typnamespace=sch.oid
WHERE
        col.attrelid = 'foo.bar'::regclass  --this is used to filter the table's name
    AND NOT col.attisdropped
    AND col.attnum>0
ORDER BY
    col.attnum
;