On 01.03.2016 22:02, Bruce Momjian wrote:
On Tue, Mar 1, 2016 at 07:56:58PM +0100, Petr Jelinek wrote:Note that I am not saying that other discussed approaches are any better, I am saying that we should know approximately what we actually want and not just beat FDWs with a hammer and hope sharding will eventually emerge and call that the plan.I will say it again --- FDWs are the only sharding method I can think of that has a chance of being accepted into Postgres core. It is a plan, and if it fails, it fails. If is succeeds, that's good. What more do you want me to say? I know of no other way to answer the questions you asked above.
I do not understand why it can fail.FDW approach may be not flexible enough for building optimal distributed query execution plans for complex OLAP queries. But for simple queries it should work fine. Simple queries corresponds OLTP and simple OLAP. For OLTP we definitely need transaction manager to provide global consistency. And we have actually prototype of integration postgres_fdw with out pg_dtm and pg_tsdtm transaction managers.
The results are quite IMHO promising (see attached diagram). -- Konstantin Knizhnik Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
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