MySql - 获取需要在当前分钟运行的任务

Question

Situation:

I have a table with tasks (which need to run at different intervals) and two php scripts (initator.php & worker.php). The initiator script is run every minute by cron and the intervals are stored in a column together with the tasks.

The initiator script should check which tasks should be send to the worker script.

so the question is: How could I determine which tasks need to be run in the current minute?

I tried it with a 'next' column (mysql timestamp), the initiator script checks if the next column matches the current date without seconds but I think this isn't a good solution because of delays and execution times.

Answer 1

I don't understand your explanation of why you think "next" is a bad idea.

A key question is how scalable the solution needs to be. If you can prove that you will never have more than 20 records, then its not too onerous to read each task record and calculate the next scheduled time / check if it falls within a particular window. But when you get to hundreds of records, then it's a very different story. There's no way to create an index which can be used by the DBMS in the absence of a next-planned-execution-time attribute.