Polidoro - Scala sugar on top of the Astyanax java client for Cassandra in the style of Cascal.
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Readme.markdown

Polidoro

Polidoro was the son of Astyanax.

As far as this repo goes Polidoro is a Cassandra client written in Scala. It is a light sugar over Astyanax in the style of Cascal.

Features

  • Simple data model with support for Composite columns
  • Direct access to Astyanax for complex tasks

API Docs

Overview of Use

To use Polidoro you create a class or classes that model your family groups (those column families in the same keyspace). Family groups are contained in a CassConnector which holds the Astyanax context. From there you create your data columns as needed for insert or delete. You can use a TestableCassConnector to set up your connection for spawning a daemonized Cassandra instance for testing with specs2.

The tests set up in the repo demonstrate a connector (SpotAsty) with a family group (DemonstrationFG) along with the setup needed for testing (csh.testing.DemoClusterLoader, csh.testing.keyspaces.Demonstration)

Data Model

(Use import com.spotright.polidoro.model._ to enable code below.)

Polidoro uses the data model put forward by Cascal. A column path is created using the '' operator.

val col = cfPeople \ "Lanny Ripple" \ ("state", "TX")

Composite constructs are supported at the key and columnname level

import CompositeFactory.CF
val col = scfUsers \ "Ripple" \ (CF("Lanny", "state"), "TX")

Once you have enough of a column path to operate on you can call various methods to get, list, or mutate. Getting a value (returning an Option[cna.model.Column[N]]) and listing (returning a cna.model.ColumnList[N]) are straightforward

val maybeCol = (cfPeople \ "Lanny Ripple" \ "state").get

and

import com.spotright.polidoro.serialization._
val cols = (scfUsers \ "Ripple") listWith CompStr2.serdes

As an aside Astyanax cares about the key, column name, and value types. These have consistently been named K, N, and V respectively in the Polidoro code.

For mutation the simplest way is to use csh.model case classes that descend from Operation and then batch the results.

val ops = List(
  Insert(cfPeople \ "Dave Angulo" \ ("state", "CO"),
  Delete(cfPeople \ "Dave Angulo" \ "status"),
  IncrCounter(cfCounters \ "typos" \ ("colnames", 1L)),
  IncrCounter(cfCounters \ "typos" \ ("keys", 1L))
)

SpotAsty.batch(ops)

Mutation is supported directly on columns (see csh.model.ColumnPath) but in practice we find it simpler to batch().