Re: logical replication busy-waiting on a lock

On 2017-06-01 14:17:44 +0200, Petr Jelinek wrote:
> Thinking more about this, I am not convinced it's a good idea to change
> exports this late in the cycle. I still think it's best to do the xid
> assignment only when the snapshot is actually exported but don't assign
> xid when the export is only used by the local session (the new option in
> PG10). That's one line change which impacts only logical
> replication/decoding as opposed to everything else which uses exported
> snapshots.

I'm not quite convinced by this argument. Exported snapshot contents
are ephemeral, we can change the format at any time. The wait is fairly
annoying for every user of logical decoding. For me the combination of
those two fact implies that we should rather fix this properly.

- Andres