On 17 July 2015 at 15:02, Amit Bondwal <bondwal.amit@xxxxxxxxx> wrote: > I looked at pg_shard, as per my understanding it is for nosql data, in our > case we are going to use postgresql RDBMS features without nosql, pg_shard > have lot on limitation as per our case. You'll find that _most_ products have a lot of limitations when doing things like horizontal scaling. BDR is no exception either. > 1. If start with postgresql 9.4 database, later can I upgrade it to BDR with > these already large table, can I distribute these tables or shard them. You need a patched PostgreSQL 9.4 if you're going to use BDR because it relies on a bunch of functionality that didn't make it into the 9.4 release. (Some didn't make it into 9.5 either). That patched PostgreSQL can be used like normal PostgreSQL 9.4, but it's not 100% on-disk compatible. You have to do a dump and reload to convert to or from stock community PostgreSQL, you can't pg_upgrade or otherwise convert in-place. You can run normal PostgreSQL applications on a standalone database on the BDR-patched PostgreSQL 9.4 by just not installing the BDR extension in the database. You can then activate BDR later. Be aware, though, that BDR imposes quite a few limitations on what the app can do when it comes to DDL. If you activate BDR later, you might find that things you were expecting to work and that worked fine before stop working. I'd strongly suggest planning to deploy with BDR from the start if you're going to use it at all. > 2. how can I distribute some of tables on my slave nodes, if it have any > limitations please let me know. BDR doesn't support sharding. A table can be on all nodes or - using replication sets - some subset of nodes, but it's the whole table or none of it. You can partition the table and shard the partitions using replication sets, but then each node will only see a subset of the data. There's no transparent cross-node querying. You could try to combine foreign data wrappers and inheritance with partitioning, but by then you're playing database jenga and things will come toppling down very, very hard. > 3. if I started with 4 or 5 node cluster with one master and rest of slave > nodes, how can I take backup of this distributed database to one of my other > server or backup location. pg_dump > Please suggest me what would be the best approch for this. >From your description it sounds like BDR is not particularly suitable for your use case at this time. We're looking at adding sharding down the track, but it's quite a way down the track because there's a fair bit of work on making sure the core functionality is rock solid and easy to manage. -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
