cron – select * from depesz;

How to run some tasks without user intervention, at specific times? – part 2

Couple of days earlier I wrote about tools to run tasks in db at scheduled times.

In writing this I missed pg_cron. So let's look into it now.

Every now and then someone complains (me included) that PostgreSQL doesn't have job scheduler.

This is true, to some extent. I'll try to show you couple of approaches to solving this particular problem.

Some time ago someone on irc asked about creating fast counters for something (banners I think).

I talked with her (him?) about it, but figured, I can as well write a blogpost, so others can use it too.

simple brainteaser. take no more than 30 seconds to think about it:

using standard cron installed on your unix system, how often would this command be run:

*/57 * * * * command

? if you choose to answer in comments, please supply version of cron that your system is using.

simple brain teaser:

given standard unix crontab what is the longest possible interval between calls to the same program?

for example:

15 */2 * * * /bin/echo x

has interval 2 hours.

what is the longest possible? and how to make it?