#!/usr/bin/python3
import argparse
import psycopg2
import psycopg2.extras

ap = argparse.ArgumentParser()
ap.add_argument("--dbname")
ap.add_argument("--user")
ap.add_argument("--host")
ap.add_argument("--schema", default="public")
ap.add_argument("table")

args = ap.parse_args()

db = psycopg2.connect(host=args.host, dbname=args.dbname, user=args.user)
csr = db.cursor(cursor_factory=psycopg2.extras.NamedTupleCursor)
csr.execute(
        """
        select * from information_schema.columns
        where table_schema = %s and table_name = %s
        order by ordinal_position
        """,
        (args.schema, args.table,))
for c in csr.fetchall():
    q = "select" \
        f" min(pg_column_size({c.column_name}))," \
        f" avg(pg_column_size({c.column_name}))," \
        f" max(pg_column_size({c.column_name}))" \
        f" from {args.schema}.{args.table}"
    csr.execute(q)
    r = csr.fetchone()
    print(f"{c.column_name:7s}: {c.data_type:17s} {r.min} {r.avg:4.1f} {r.max:3d}")