Guys, tell me please, where can I store/update the date/identifier of the last processed event? The fact is that I don’t need to collect all the events again at each start, it’s enough for me to receive only those that have appeared since the last poll on each request

You probably want

Stream.replication_key

- have a look at the stream state docs.

Why do they write that this is only for debugging?

I guess because it's more of a deep-dive into the state implementation. The SDK supports a number of ways to interact with state indirectly - some of which are mentioned on that page, but you might find looking at the Stream class reference more helpful.

Got it, thanks, I'll check it out