Checking if a postgresql table exists under python (and probably Psycopg2)

Question

How can I determine if a table exists using the Psycopg2 Python library? I want a true or false boolean.

Answer 1

I don't know the psycopg2 lib specifically, but the following query can be used to check for existence of a table:

SELECT EXISTS(SELECT 1 FROM information_schema.tables 
              WHERE table_catalog='DB_NAME' AND 
                    table_schema='public' AND 
                    table_name='TABLE_NAME');

The advantage of using information_schema over selecting directly from the pg_* tables is some degree of portability of the query.

Answer 2

The first answer did not work for me. I found success checking for the relation in pg_class:

def table_exists(con, table_str):
    exists = False
    try:
        cur = con.cursor()
        cur.execute("select exists(select relname from pg_class where relname='" + table_str + "')")
        exists = cur.fetchone()[0]
        print exists
        cur.close()
    except psycopg2.Error as e:
        print e
    return exists