FYI there is an everywhere strategy waiting to be accepted:
https://issues.apache.org/jira/browse/CASSANDRA-12629
On Sat, 8 Oct 2016 at 10:56 Vladimir Yudovin <vla...@winguzone.com> wrote:
Well, it can be useful in some scenarios - e.g. temporary tables on nearest
or the same node.
Best regards, Vladimir Yudovin,
Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
Launch your cluster in minutes.
---- On Sat, 08 Oct 2016 13:44:00 -0400 Jeff Jirsa<jji...@gmail.com>
wrote ----
I'm sure that's what he meant, I just disagree that it sounds useful
--
Jeff Jirsa
> On Oct 8, 2016, at 10:33 AM, Vladimir Yudovin <vla...@winguzone.com>
wrote:
>
> As far as I understand Edward meant to have option determinate actual
storage node on client side, by driver, disregarding key hash/tokens
mechanism.
>
> Best regards, Vladimir Yudovin,
> Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
> Launch your cluster in minutes.
>
>
>
>
> ---- On Sat, 08 Oct 2016 13:17:14 -0400 Jeff Jirsa &
amp;lt;jji...@gmail.com&gt; wrote ----
>
> That sounds awful, especially since you could just use SimpleStrategy
with RF=1 and then bootstrap / decom would handle resharding for you as
expected.
>
> --
> Jeff Jirsa
>
>
> &gt; On Oct 8, 2016, at 10:09 AM, Edward Capriolo &
amp;lt;edlinuxg...@gmail.com&gt; wrote:
> &gt;
> &gt; I have contemplated using LocalStrategy as a "do it yourself
client side
> &gt; sharding system".
> &gt;
> &gt; On Sat, Oct 8, 2016 at 12:37 AM, Vladimir Yudovin &
amp;lt;vla...@winguzone.com&gt;
> &gt; wrote:
> &gt;
> &gt;&gt; Hi Prasenjit,
> &gt;&gt; I would like to get the replication factors of the
key-spaces using the
> &gt;&gt; strategies in the same way we get the replication
factors for Simple and
> &gt;&gt; NetworkTopology.
> &gt;&gt; Actually LocalSarategy has no replication factor:
> &gt;&gt;
> &gt;&gt; SELECT * FROM system_schema.keyspaces WHERE
keyspace_name IN ('system',
> &gt;&gt; 'system_schema');
> &gt;&gt; keyspace_name | durable_writes | replication
> &gt;&gt;
---------------+----------------+---------------------------
> &gt;&gt; -----------------------------------------
> &gt;&gt; system | True | {'class':
> &gt;&gt; 'org.apache.cassandra.locator.LocalStrategy'}
> &gt;&gt; system_schema | True | {'class':
> &gt;&gt; 'org.apache.cassandra.locator.LocalStrategy'}
> &gt;&gt;
> &gt;&gt;
> &gt;&gt; It's used for internal tables and not accessible to
users:
> &gt;&gt;
> &gt;&gt; CREATE KEYSPACE excel WITH replication = {'class':
'LocalStrategy'};
> &gt;&gt; ConfigurationException: Unable to use given strategy
class: LocalStrategy
> &gt;&gt; is reserved for internal use.
> &gt;&gt;
> &gt;&gt;
> &gt;&gt; Best regards, Vladimir Yudovin,
> &gt;&gt; Winguzone - Hosted Cloud Cassandra on Azure and
SoftLayer.
> &gt;&gt; Launch your cluster in minutes.
> &gt;&gt;
> &gt;&gt;
> &gt;&gt;
> &gt;&gt;
> &gt;&gt; ---- On Fri, 07 Oct 2016 17:06:09 -0400 Prasenjit
> &gt;&gt; Sarkar&amp;lt;prasenjit.sar...@datos.io&amp;gt;
wrote ----
> &gt;&gt;
> &gt;&gt; Thanks Vlad and Jeremiah.
> &gt;&gt;
> &gt;&gt; There were questions about support, so let me address
that in more detail.
> &gt;&gt;
> &gt;&gt; If I look at the latest Cassandra python driver, the
support for
> &gt;&gt; LocalStrategy is very limited (code snippet shown
below) and the support
> &gt;&gt; for EverywhereStrategy is non-existent. By limited I
mean that the
> &gt;&gt; Cassandra python driver only provides the name of the
strategy for
> &gt;&gt; LocalStrategy and not much else.
> &gt;&gt;
> &gt;&gt; What I would like (and happy to help) is for the
Cassandra python driver to
> &gt;&gt; provide support for Local and Everywhere to the same
extent it is provided
> &gt;&gt; for Simple and NetworkTopology. I understand that
token aware routing is
> &gt;&gt; not applicable to either strategy but I would like to
get the replication
> &gt;&gt; factors of the key-spaces using the strategies in the
same way we get the
> &gt;&gt; replication factors for Simple and NetworkTopology.
> &gt;&gt;
> &gt;&gt; Hope this helps,
> &gt;&gt; Prasenjit
> &gt;&gt;
> &gt;&gt;
> &gt;&gt; class LocalStrategy(ReplicationStrategy):
> &gt;&gt; def __init__(self, options_map):
> &gt;&gt; pass
> &gt;&gt; def make_token_replica_map(self, token_to_host_owner,
ring):
> &gt;&gt; return {}
> &gt;&gt; def export_for_schema(self):
> &gt;&gt; """
> &gt;&gt; Returns a string version of these replication options
which are
> &gt;&gt; suitable for use in a CREATE KEYSPACE statement.
> &gt;&gt; """
> &gt;&gt; return "{'class': 'LocalStrategy'}"
> &gt;&gt; def __eq__(self, other):
> &gt;&gt; return isinstance(other, LocalStrategy)
> &gt;&gt;
> &gt;&gt; On Fri, Oct 7, 2016 at 11:56 AM, Jeremiah D Jordan
&amp;lt;
> &gt;&gt; jeremiah.jor...@gmail.com&amp;gt; wrote:
> &gt;&gt;
> &gt;&gt; &amp;gt; What kind of support are you thinking
of? All drivers should support
> &gt;&gt; them
> &gt;&gt; &amp;gt; already, drivers shouldn’t care about
replication strategy except when
> &gt;&gt; &amp;gt; trying to do token aware routing.
> &gt;&gt; &amp;gt; But since anyone can make a custom
replication strategy, drivers that
> &gt;&gt; do
> &gt;&gt; &amp;gt; token aware routing just need to handle
falling back to not doing
> &gt;&gt; token
> &gt;&gt; &amp;gt; aware routing if a replication strategy
they don’t know about is in
> &gt;&gt; use.
> &gt;&gt; &amp;gt; All the open sources drivers I know of
do this, so they should all
> &gt;&gt; &amp;gt; “support” those strategies already.
> &gt;&gt; &amp;gt;
> &gt;&gt; &amp;gt; -Jeremiah
> &gt;&gt; &amp;gt;
> &gt;&gt; &amp;gt; &amp;gt; On Oct 7, 2016, at 1:02 PM,
Prasenjit Sarkar &amp;
> &gt;&gt; lt;prasenjit.sar...@datos.io&amp;gt;
> &gt;&gt; &amp;gt; wrote:
> &gt;&gt; &amp;gt; &amp;gt;
> &gt;&gt; &amp;gt; &amp;gt; Hi everyone,
> &gt;&gt; &amp;gt; &amp;gt;
> &gt;&gt; &amp;gt; &amp;gt; To the best of my
understanding that Datastax has proprietary
> &gt;&gt; replication
> &gt;&gt; &amp;gt; &amp;gt; strategies: Local and
Everywhere which are not part of the open
> &gt;&gt; source
> &gt;&gt; &amp;gt; &amp;gt; Apache Cassandra project.
> &gt;&gt; &amp;gt; &amp;gt;
> &gt;&gt; &amp;gt; &amp;gt; Do we know of any plans in
the open source Cassandra driver
> &gt;&gt; community to
> &gt;&gt; &amp;gt; &amp;gt; support these two
replication strategies? Would Datastax have a
> &gt;&gt; licensing
> &gt;&gt; &amp;gt; &amp;gt; concern if the open source
driver community supported these
> &gt;&gt; strategies?
> &gt;&gt; &amp;gt; I'm
> &gt;&gt; &amp;gt; &amp;gt; fairly new here and would
like to understand the dynamics.
> &gt;&gt; &amp;gt; &amp;gt;
> &gt;&gt; &amp;gt; &amp;gt; Thanks,
> &gt;&gt; &amp;gt; &amp;gt; Prasenjit
> &gt;&gt; &amp;gt;
> &gt;&gt; &amp;gt;
> &gt;&gt;
> &gt;&gt;
> &gt;&gt;
> &gt;&gt;
> &gt;&gt;
> &gt;&gt;
>
>
>
>
>
--
Ben Bromhead
CTO | Instaclustr <https://www.instaclustr.com/>
+1 650 284 9692
Managed Cassandra / Spark on AWS, Azure and Softlayer
