Re: GSoC 2018
От | Alex Kliukin |
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Тема | Re: GSoC 2018 |
Дата | |
Msg-id | 1513348366.1924171.1206181304.4AD5D0CE@webmail.messagingengine.com обсуждение исходный текст |
Ответ на | Re: GSoC 2018 (Stephen Frost <sfrost@snowman.net>) |
Ответы |
Re: GSoC 2018
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Список | pgsql-hackers |
Hello, On Fri, Dec 15, 2017, at 14:30, Stephen Frost wrote: > Aleksander, > > * Aleksander Alekseev (a.alekseev@postgrespro.ru) wrote: > > > Regarding the difficulty of the project - in fact it's not that > > difficult. Particularly this project can rely on external tools, e.g. > > use Consul for service discovery and leader election based on > > leader-lease approach (implementation [1]). Having this the only thing > > is missing is automatic replica promoting and (optionally) > > re-configuring of HAProxy / pgbouncer / whatever. Yes, and lots of > > Jepsen-like test of course. I believe it's not such a complicated > > project. Does it make sense to address the limitations of the logical replication first, i.e. inability to replicate DDL, sequences and so on? > > What you're talking about is rebuilding Patroni, but adding more into it > than even Patroni tries to do, building it on Logical Replication > instead of physical replication, and calling it simple and something > that could get into core PostgreSQL over a 12 week GSoC project. I've > certainly got doubts about that, even if we decide that it'd be an > external-to-PG project (like Patroni). > > What might be interesting is seeing if Logical Replication could be > added to Patroni as an option and then building on that.. Having > someone involved in the Patroni project would be the right way to go > about proposing that though to see what they think of it. That would > also be much more sensible as a GSoC project, since it'd be an addition > to an existing project and not more-or-less starting a whole new > project. Right now logical replication and physical replication-based HA tools don't work together nicely, since logical replication position is not propagated to the promoted replica (I think Craig Ringer has been tackling this issue for a few releases already, the latest set of patches I could find is https://commitfest.postgresql.org/15/788/). Perhaps there is opportunity for a GSoC student to help fixing it. Until then we cannot use logical replication for HA, and even doing something simpler like automating creation of logical replicas in Patroni makes little sense, as they are doomed to be reinitialized on every failover. -- Sincerely, Alex
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