On Wed, Mar 2, 2016 at 9:53 PM, Josh berkus <j...@agliodbs.com> wrote:
> On 02/24/2016 01:22 AM, Konstantin Knizhnik wrote: > >> Sorry, but based on this plan it is possible to make a conclusion that >> there are only two possible cluster solutions for Postgres: >> XC/XL and FDW-based. From my point of view there are much more >> possible alternatives. >> > > Definitely. > > Currently we have five approaches to sharding inside postgres in the > field, in chronological order: > > 1. Greenplum's executor-based approach with motion nodes > > 2. Skype's function-based approach (PL/proxy) > > 3. XC/XL's approach, which I believe is also query executor-based > > 4. CitusDB's pg_shard which is based on query hooks > > 5. FDW-based (currently theoretical) > > One of the things which causes bad reactions and arguments, Bruce, is that > a lot of your posts and presentations detailing plans for the FDW approach > carry the subtext that all four of the other approaches are dead ends and > not worth considering. Given that the other approaches, whatever their > limitations, have working code in the field and the FDW approach does not, > that's more than a little offensive. > > If we want to move forwards on serious work on FDW-based sharding, the > folks working on it should stop treating it as a "fait accompli" that this > is the Chosen Way for the PostgreSQL project. Otherwise, you'll spend all > of your time arguing that point instead of working on features that matter. > > Bruce made a long comparison with built-in replication, but there's a big > difference here. We decided that WAL-based replication was the way to go > for built-in as a community decision here on -hackers and at various > conferences. Both the plan and the implementation for replication > transcended company backing, involving even active competitors, and > involved discussions with maintainers of the older replication projects. > > In contrast, this FDW plan *still* feels very much like a small group made > up of employees of only two companies came up with it in private and > decided that it should be the plan for the whole project. I know that > Bruce and others have good reasons for starting the FDW project, but there > hasn't been much of an attempt to obtain community consensus around it. If > Bruce and others want contributors to work on FDWs instead of other > sharding approaches, then they need to win over those people as to why they > should do that. It's how this community works. > > Alternately, you can just work on the individual FDW features, which > *everyone* thinks are a good idea, and when most of them are done, > FDW-based scaleout will be such an obvious solution that nobody will argue > with it. +1 Thank you, Josh. I think this is excellent summary for conversation about FDW-based sharding. ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
