Manage cron schedules in runtime

[AntonKarabaza]

@janbjorge Is there an option to manage cron schedules in runtime?

For example in case if it is required to add new schedule via API request which would not require pgqueuer worker restart.

From what I see in current implementation - that is not possible since schedules are stored in worker memory and used to pull upcoming schedules from database.
However I'm curios if this required to have schedule key as entrypoint + expression?
If schedule key would be only entrypoint, then it would be possible to add new schedules for "know" (registered) schedule entrypoints just by adding records to schedule table.

[janbjorge]

As of now, I don’t think it’s possible to manage cron schedules dynamically at runtime. However, it’s an interesting idea! I believe the reason I made (entrypoint, expression) unique might have been to avoid the complexity of handling overlapping crontabs for the same entry point.

For example, if two different cron expressions were defined for the same entry point:

• Should the entry point be triggered twice if both schedules overlap?
• If not, how do we prioritize or merge the schedules?

These considerations add a layer of complexity to the runtime behavior, which is likely why I opted for the current design. Revisiting this with fresh eyes could open up interesting possibilities.

Another thing to consider is how 'new' code would be loaded and executed for dynamically added schedules. Since workers load the code for entry points at startup, adding a new schedule via an API raises questions like:

• How would workers discover and execute new code that wasn’t loaded at startup?
• Should workers dynamically monitor for changes? If so, how would that be implemented safely and efficiently?
• Would this require storing code as part of the schedule metadata or relying on an external mechanism to deploy and load updates?

These challenges highlight the trade-offs in introducing dynamic schedule management—it adds flexibility but also complexity to the system. That said, it’s definitely a feature worth exploring if runtime schedule updates become a priority. Thanks for bringing this up!