set transaction\query timeout in psycopg2?

Question

Is there a way to set a timeout in psycopg2 for db transactions or for db queries?

A sample use-case:
Heroku limits django web requests to 30sec

Answer 1

You can set the timeout at connection time using the options parameter. The syntax is a bit weird:

>>> import psycopg2
>>> cnn = psycopg2.connect("dbname=test options='-c statement_timeout=1000'")
>>> cur = cnn.cursor()
>>> cur.execute("select pg_sleep(2000)")
Traceback (most recent call last):
  File "", line 1, in 
psycopg2.extensions.QueryCanceledError: canceling statement due to statement timeout

it can also be set using an env variable:

>>> import os
>>> os.environ['PGOPTIONS'] = '-c statement_timeout=1000'
>>> import psycopg2
>>> cnn = psycopg2.connect("dbname=test")
>>> cur = cnn.cursor()
>>> cur.execute("select pg_sleep(2000)")
Traceback (most recent call last):
  File "", line 1, in 
psycopg2.extensions.QueryCanceledError: canceling statement due to statement timeout