How robust is the 1P1C transaction relay on Bitcoin Core 28.0?

What does non-saving mean in this context?

Non-active means “we are missing things because we are not guaranteed, especially in the presence of enemies or when the volume is really high.” Also, the “package relay” in quotes refers to the fact that there is no package relay protocolpart of the opportunistic logic that can be seen when an orphanage transaction happens to be CPFping a failed transaction with low refueling.

Perhaps a good similarity is if you’re a restaurant chef who doesn’t have a dedicated server. Once you’re finished cooking, you can opportunistically bring food to the table, which is often fine, but delayed during rush hour. The ticket system is also not evaluated. If you can’t keep all the tickets, then random tickets will fall to the ground and forget to order them. One annoying customer can ruin someone else’s dining experience by ordering 100 diet cokes.

We can hire others to serve food. It certainly makes the restaurant more efficient (e.g. BIP 331, still WIP), but it doesn’t solve everything. Starting from 30.0, there is a strategy to limit customers to rates so they don’t forget to send out huge amounts (see “P2P: Improve Service Boundaries in Txorphanage” https://github.com/bitcoin/bitcoin/pull/31829).

Are there any situations where parents’ transactions cannot be confirmed yet?

The most important limitation of 28.0 is that Cook can only offer something very simple (1P1C package). Anything above 1P1C will not work. If the child has another unconfirmed parent, the logic of opportunism will not work, even if it is already in Mempools. This has also been changed (“Package Validation: Relax the package.

When broadcasting a transaction via SendRawTransaction, Bitcoin Core 28.0 automatically forms a 1P1C package

That’s the right thing to do. When you send a transaction to Mempool, the node does everything automatically. If it is a 0-FEE parent + child package, sendrawtransaction You might complain about the fees, so you submitpackage RPC (equivalent to multi-transactions sendrawtransaction (with a very similar API). RPCs also accept single transactions, so it may be most convenient to use them all the time.