topic Re: Nuxeo with a fault-tolerant PostgreSQL configuration in Nuxeo Forum

Nuxeo with a fault-tolerant PostgreSQL configuration

ron_1 — Wed, 03 Oct 2012 23:13:33 GMT

With the recent release of PostgreSQL 9.2, repmgr 2.0-beta (http://www.postgresql.org/about/news/1411/), and JDBC4 Postgresql Driver Version 9.2-1000 (with basic failover support), does Nuxeo have plans to test and/or document a fault-tolerant Nuxeo/PostgreSQL configuration with master/hot-standby PostgreSQL servers and automatic failover.

Re: Nuxeo with a fault-tolerant PostgreSQL configuration

Florent_Guillau — Tue, 16 Oct 2012 23:05:48 GMT

We'd love to but the problem is that the hot standby is still read-only, which prevents even a transaction BEGIN from being executed on it. As the Nuxeo framework is pluggable, we don't have any way of knowing for a given HTTP request if the whole work to be executed will be read-only w.r.t. the database, or if somewhere a listener will want to write data. So in all cases we have to start a transaction very early, which prevents a hot standby from being used.

A way to improve this would be to have at the URL level some way of discriminating between requests that are going to be purely read-only and those who don't, but that's not something we have today.

Postgres-XC may be a better bet, but we haven't tested it yet.

Re: Nuxeo with a fault-tolerant PostgreSQL configuration

ron_1 — Thu, 18 Oct 2012 05:01:30 GMT

I was specifically inquiring about high-availability/failover as opposed to increased scalability by leveraging the hot-standby for queries.