August 2013 Summaries

Cassandra triggers are a feature introduced in version 2.0.0, but they are still experimental and not finalized until at least version 2.1. They rely on logged batches to provide atomicity and eventual consistency. Triggers execute before mutations are applied, allowing alteration or augmentation of the original changes. However, triggers on counter tables are generally not supported due to idempotency issues. There are multiple potential use cases for Cassandra triggers, but improvements such as parametrization and CQL3 support are needed before they can be declared production-ready.

The text describes a process of using Cassandra and Pig for data analysis, specifically to answer the question "What portion of California is covered by libraries?". It explains how to load library service outlet data into Cassandra, create a table schema, and perform queries on the data. The author then moves to PIG for more advanced queries, demonstrating how to filter and count rows based on specific criteria. Finally, it shows how to save the processed data back into Cassandra using CqlStorage.

OpsCenter is a tool used to manage and monitor Cassandra and DataStax Enterprise clusters. It has three main components: User Interface (UI), OpsCenter Daemon, and OpsCenter Agent. The UI is self-contained in the browser and interacts with the API exposed by the OpsCenter Daemon. The daemon serves the UI component, exposes a REST API for interaction, and gathers cluster information via thrift or agents. The agent collects node information, manages performance data, and acts as a proxy for Cassandra's JMX management functions. Encryption of communication is enabled by default through SSL, with optional support for other types of communication.

gltail by Erlend Simonsen is a real-time log viewer written in Ruby, offering an engaging live view of log data from multiple servers. It assigns log entries to blocks/labels displayed on the border and tracks counts/averages per entry. New log entries are shown as events or activities with differently sized circles representing their size. To use gltail, set up a working Apache Cassandra™/Datastax Enterprise ring and download gltail from GitHub. Customize the gl_tail.yaml file to enable gltail to read log files and parse them. The parser for the log file defines regular expressions that extract specific information, which can be added to particular blocks or new ones. This tool is useful for visualizing correlations between events and alerting about specific errors in a way that tracks occurrences.