cassandra

Cassandra implementation of Broker interface

The API was tested with Cassandra 3 and supports:

• UDT (User Defined Types) / embedded structs and honors gocql.Marshaler/gocql.Unmarshaler
• handling all primitive types (like int aliases , IP address);
  • net.IP can be stored as ipnet
  • net.IPNet can be stored with a MarshalCQL/UnmarshalCQL wrapper go structure
• dumping all rows except for Table
• quering by secondary indexes
• mocking of gocql behavior (using gockle library)in automated unit tests

Cassandra Timeouts

The API will allow the client to configure either single node or multi-node cluster. Also, the client can configure following timeouts:

• DialTimeout
  • Initial connection timeout, used during initial dial to server
  • Default value is 600ms
• OpTimeout
  • Connection timeout, used during executing query
  • Default value is 600ms
• RedialInterval
  • If not zero, gocql attempt to reconnect known DOWN nodes in every ReconnectSleep (ReconnectInterval)
  • Default value is 60s
• Example

    config := &cassandra.Config{
        Endpoints:      127.0.0.1,
        Port:           9042,
        DialTimeout:    600 * time.Millisecond,
        OpTimeout:      600 * time.Millisecond,
        RedialInterval: 60 * time.Second,
    }

    clientConfig, err := cassandra.ConfigToClientConfig(config)

The timeout parameters are defined here config.go

Supported by underlying gocql structure ClusterConfig

Cassandra Data Consistency

The API will allow the client to configure consistency level for both

• Session
• Query (to be implemented)

Supported by underlying gocql structure Session

Factors to be considered for achieving desired consistency level.

• Replication strategy

  • A replication strategy determines the nodes where replicas are placed.
    • SimpleStrategy: Use for a single data center only.
    • NetworkTopologyStrategy: Used for more than one data center.

• Replication factor

  • The total number of replicas across the cluster is referred to as the replication factor.
  • A replication factor of 1 means that there is only one copy of each row on one node.
  • A replication factor of 2 means that there are two copies of each row, and each copy is stored on a different node.
  • The replication factor should not exceed the number of nodes in the cluster.

• To achieve Quorum

  • Quorum = (sum_of_replication_factors / 2) + 1
  • (nodes_written + nodes_read) > replication_factor

• References

  • Apache Cassandra
  • Cassandra Data Replication
  • Cassandra Consistency Levels