[Tarantool-patches] [PATCH 09/15] tx: introduce prepare sequence number

[Aleksandr Lyapunov]

On 05.07.2020 20:05, Vladislav Shpilevoy wrote:
> Thanks for the patch!
>
> What are these psns? What are the difference with txn->id and
> with lsn?

I need an ID for ordering transactions, for answering a simple
question - which TX is earlier in order of serialization.

txn->id gives us order of creation of TXs, it's not suitable because
TXs could be prepared in different order.

LSN is good, it give us a correct order, but there's a problem with it:
it becomes known after wal writer call, and I need that order before
wal writer finishes.