Merge pull request #680 from lexicalunit/update-cassandra-example

Updates Cassandra example documentation.

docs/content/Cassandra-Deep-Storage.md

+---
+layout: doc_page
+---
+
+## Introduction
+Druid can use Cassandra as a deep storage mechanism. Segments and their metadata are stored in Cassandra in two tables:
+`index_storage` and `descriptor_storage`.  Underneath the hood, the Cassandra integration leverages Astyanax.  The 
+index storage table is a [Chunked Object](https://github.com/Netflix/astyanax/wiki/Chunked-Object-Store) repository. It contains
+compressed segments for distribution to historical nodes.  Since segments can be large, the Chunked Object storage allows the integration to multi-thread
+the write to Cassandra, and spreads the data across all the nodes in a cluster.  The descriptor storage table is a normal C* table that 
+stores the segment metadatak.  
+
+## Schema
+Below are the create statements for each:
+
+```sql
+CREATE TABLE index_storage(key text,
+                           chunk text,
+                           value blob,
+                           PRIMARY KEY (key, chunk)) WITH COMPACT STORAGE;
+
+CREATE TABLE descriptor_storage(key varchar,
+                                lastModified timestamp,
+                                descriptor varchar,
+                                PRIMARY KEY (key)) WITH COMPACT STORAGE;
+```
+
+## Getting Started
+First create the schema above. I use a new keyspace called `druid` for this purpose, which can be created using the
+[Cassandra CQL `CREATE KEYSPACE`](http://www.datastax.com/documentation/cql/3.1/cql/cql_reference/create_keyspace_r.html) command.
+
+Then, add the following to your historical and realtime runtime properties files to enable a Cassandra backend.
+
+```properties
+druid.extensions.coordinates=["io.druid.extensions:druid-cassandra-storage:<druid version>"]
+druid.storage.type=c*
+druid.storage.host=localhost:9160
+druid.storage.keyspace=druid
+```
+
+Use the `druid-development@googlegroups.com` mailing list if you have questions,
+or feel free to reach out directly: `bone@alumni.brown.edu`.
+
+

docs/content/Deep-Storage.md

@@ -47,3 +47,11 @@ druid.storage.storageDirectory=<directory for storing segments>
 Note that you should generally set `druid.storage.storageDirectory` to something different from `druid.segmentCache.locations` and `druid.segmentCache.infoDir`.
 
 If you are using the Hadoop indexer in local mode, then just give it a local file as your output directory and it will work.
+
+
+## Cassandra
+
+[Apache Cassandra](http://www.datastax.com/what-we-offer/products-services/datastax-enterprise/apache-cassandra) can also be leveraged for deep storage.  This requires some additional druid configuration as well as setting up the necessary schema within a Cassandra keystore.
+
+For more information on using Cassandra as deep storage, see [Cassandra Deep Storage](Cassandra-Deep-Storage.html).
+

examples/cassandra/README.md

-## Introduction
-Druid can use Cassandra as a deep storage mechanism. Segments and their metadata are stored in Cassandra in two tables:
-`index_storage` and `descriptor_storage`.  Underneath the hood, the Cassandra integration leverages Astyanax.  The 
-index storage table is a [Chunked Object](https://github.com/Netflix/astyanax/wiki/Chunked-Object-Store) repository. It contains
-compressed segments for distribution to historical nodes.  Since segments can be large, the Chunked Object storage allows the integration to multi-thread
-the write to Cassandra, and spreads the data across all the nodes in a cluster.  The descriptor storage table is a normal C* table that 
-stores the segment metadatak.  
-
-## Schema
-Below are the create statements for each:
-
-
-
-    CREATE TABLE index_storage ( key text, chunk text, value blob, PRIMARY KEY (key, chunk)) WITH COMPACT STORAGE;
-
-    CREATE TABLE descriptor_storage ( key varchar, lastModified timestamp, descriptor varchar, PRIMARY KEY (key) ) WITH COMPACT STORAGE;
-
-
-## Getting Started
-First create the schema above.  (I use a new keyspace called `druid`) 
-
-Then, add the following properties to your properties file to enable a Cassandra 
-backend.
-
-    druid.storage.cassandra=true
-    druid.storage.cassandra.host=localhost:9160
-    druid.storage.cassandra.keyspace=druid
-
-Use the `druid-development@googlegroups.com` mailing list if you have questions,
-or feel free to reach out directly: `bone@alumni.brown.edu`.
+## Example Prerequisite
 
+The code in this example assumes Cassandra has been configured as deep storage for Druid.
 
+For details on how to accomplish this, see [Cassandra Deep Storage](../../docs/content/Cassandra-Deep-Storage.md).