On 2016-01-20 15:11:06 +0800, Craig Ringer wrote: > Unfortunately it's not particularly simple and nobody seems to have time to > implement it.
FWIW, I don't think it's *that* hard. > As Álvaro pointed out, sometimes you have to do the work if > you want the change to happen. Or find someone with the existing skills and > convince them to want to do it, but most of those people are already very, > very busy. > > As part of the failover slots work Simon noted that: > > "To prevent needed rows from being removed we need we would need to enhance > hot_standby_feedback so it sends both xmin and catalog_xmin to the master." > > ... which means a protocol change in the walsender protocol. So you're > looking at that plus the other comment given above, that Not a huge problem though. > "We need to be able to correctly and quickly identify the timeline a LSN > belongs to" > > .... which is new internal infrastructure and new state in the replica that > must be maintained. Probably persistently. I think it just needs a more efficient lookup structure over the existing tliOfPointInHistory(), the data is all there. > (On a side note, failover slots probably won't be usable from a standby > either. They have to write to WAL and you can't write to WAL from a > standby. So if slot support is ever added on a standby it'll probably be > ephemeral slots only.) ephemeral slots are a different thing. Anyway, at this point failover slots aren't really proposed / have an agreed upon design yet, so it's a bit hard to take them into account. Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers