#!/usr/local/bin/python3
# -*- coding: utf-8 -*-

# $ yum install -y postgresql10-devel
# $ pip install psycopg2-binary

import sys
from psycopg2 import pool
from psycopg2 import extras

try:
    pooldb = pool.SimpleConnectionPool(
        host = PG_HOST,
        port = 5432,
        user = PG_USER,
        password = PG_USER_PASS,
        database = PG_DB,
        minconn = 1,
        maxconn = 5
    )

    conn = pooldb.getconn()
except:
    raise

try:
    with conn.cursor(cursor_factory = extras.RealDictCursor) as cursor:
        sql = "SELECT version();"
        cursor.execute(sql)
        result = cursor.fetchone()
        print(result)
        conn.commit()
        cursor.close()
except:
    raise
finally:
    pooldb.putconn(conn)
    pooldb.closeall()