I have contemplated using LocalStrategy as a "do it yourself client side
sharding system".
On Sat, Oct 8, 2016 at 12:37 AM, Vladimir Yudovin <vla...@winguzone.com>
wrote:
> Hi Prasenjit,
> I would like to get the replication factors of the key-spaces using the
> strategies in the same way we get the replication factors for Simple and
> NetworkTopology.
> Actually LocalSarategy has no replication factor:
>
> SELECT * FROM system_schema.keyspaces WHERE keyspace_name IN ('system',
> 'system_schema');
> keyspace_name | durable_writes | replication
> ---------------+----------------+---------------------------
> -----------------------------------------
> system | True | {'class':
> 'org.apache.cassandra.locator.LocalStrategy'}
> system_schema | True | {'class':
> 'org.apache.cassandra.locator.LocalStrategy'}
>
>
> It's used for internal tables and not accessible to users:
>
> CREATE KEYSPACE excel WITH replication = {'class': 'LocalStrategy'};
> ConfigurationException: Unable to use given strategy class: LocalStrategy
> is reserved for internal use.
>
>
> Best regards, Vladimir Yudovin,
> Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
> Launch your cluster in minutes.
>
>
>
>
> ---- On Fri, 07 Oct 2016 17:06:09 -0400 Prasenjit
> Sarkar<prasenjit.sar...@datos.io> wrote ----
>
> Thanks Vlad and Jeremiah.
>
> There were questions about support, so let me address that in more detail.
>
> If I look at the latest Cassandra python driver, the support for
> LocalStrategy is very limited (code snippet shown below) and the support
> for EverywhereStrategy is non-existent. By limited I mean that the
> Cassandra python driver only provides the name of the strategy for
> LocalStrategy and not much else.
>
> What I would like (and happy to help) is for the Cassandra python driver to
> provide support for Local and Everywhere to the same extent it is provided
> for Simple and NetworkTopology. I understand that token aware routing is
> not applicable to either strategy but I would like to get the replication
> factors of the key-spaces using the strategies in the same way we get the
> replication factors for Simple and NetworkTopology.
>
> Hope this helps,
> Prasenjit
>
>
> class LocalStrategy(ReplicationStrategy):
> def __init__(self, options_map):
> pass
> def make_token_replica_map(self, token_to_host_owner, ring):
> return {}
> def export_for_schema(self):
> """
> Returns a string version of these replication options which are
> suitable for use in a CREATE KEYSPACE statement.
> """
> return "{'class': 'LocalStrategy'}"
> def __eq__(self, other):
> return isinstance(other, LocalStrategy)
>
> On Fri, Oct 7, 2016 at 11:56 AM, Jeremiah D Jordan <
> jeremiah.jor...@gmail.com> wrote:
>
> > What kind of support are you thinking of? All drivers should support
> them
> > already, drivers shouldn’t care about replication strategy except when
> > trying to do token aware routing.
> > But since anyone can make a custom replication strategy, drivers that
> do
> > token aware routing just need to handle falling back to not doing
> token
> > aware routing if a replication strategy they don’t know about is in
> use.
> > All the open sources drivers I know of do this, so they should all
> > “support” those strategies already.
> >
> > -Jeremiah
> >
> > > On Oct 7, 2016, at 1:02 PM, Prasenjit Sarkar &
> lt;prasenjit.sar...@datos.io>
> > wrote:
> > >
> > > Hi everyone,
> > >
> > > To the best of my understanding that Datastax has proprietary
> replication
> > > strategies: Local and Everywhere which are not part of the open
> source
> > > Apache Cassandra project.
> > >
> > > Do we know of any plans in the open source Cassandra driver
> community to
> > > support these two replication strategies? Would Datastax have a
> licensing
> > > concern if the open source driver community supported these
> strategies?
> > I'm
> > > fairly new here and would like to understand the dynamics.
> > >
> > > Thanks,
> > > Prasenjit
> >
> >
>
>
>
>
>
>
