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Comment by arthursilva | Hacker News Reader

PG has async/sync/hybrid replication for years already. It's not as tooled as MongoDB but there's some tools like http://www.repmgr.org/ to amend it.

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Every time I look into tools like this they are quite far behind for example AlwaysOn in MSSQL. For example, with PG I have to reseed the original master if it comes back online after an outage. It's as far as I can tell not fully automatic and transparent to me as the guy responsible for managing it. With SQL and elasticsearch+ZooKeeper for example nodes can go up and down without anyone noticing it and me not having to do anything. Is this still a place where PG is behind?

Yes and no. There are differences in the data guarantees that something like elastic search and postgresql give. So it's not really appropriate to compare those.

MS SQL does have easier tooling for replication. The setup for postrgresql is complex and it doesn't come with out of the box tools to easily manage failover and recovery as you mention. Progress is being made in making this easier, but it's still mostly in the low level functionality:

https://wiki.postgresql.org/wiki/What%27s_new_in_PostgreSQL_...

> For example, with PG I have to reseed the original master if it comes back online after an outage

pg_rewind[1] is supposed to fix this. It's moving into core for 9.5, by the way.

[1] https://github.com/vmware/pg_rewind

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