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
