Your record in ES might include data from many different tables, and figuring out what to (efficiently) update when there is a change in Postgres is not a simple task.
Anything that is a dependency in the elastisearch index should trigger a job to export to it. And since it is idempotent it doesn't matter if it accidentally exports two or ten times the same index in a bg job. Just make sure before writing that you do a quick check that you're not overriding a fresher one. So just have a freshness timestamp which is the latest timestamp of any record used in the indexing data.
Furthermore you can do a daily job to just re export a critical part of the index. Doesn't matter if it is or isn't fresh. So let's say you query all records that were modified in the last day, and trigger the export job thatnmaynincludebthat record. Even if it causes duicate work. Idempotency saves you there.
https://joist-orm.io/docs/advanced/full-text-search
Granted, currently we still do pgsearch against this derived field, but could sync it over to ES.
Are there any generic, algorithmic or even just heuristics that help with this?
It’s something I‘ve been thinking about over some time now. Any pointers, strategies and tips are appreciated.