Apache Accumulo vs Baidu Tera

Apache Accumulo is a free, open-source sorted, distributed key/value store for storing and retrieving large datasets across a cluster. It uses Apache Hadoop HDFS for data storage and Apache ZooKeeper for consensus. Each key/value pair can carry a security label, so query results can be restricted according to a user’s authorizations. Accumulo Iterators can modify key/value pairs at different stages of data management. Clusters can use one or more HDFS instances, and nodes can be added or removed as stored data changes. The project says its client API follows Long Term Maintenance releases and semantic versioning, and that each release undergoes extensive testing. The software is licensed under Apache License, Version 2.0. The downloads page lists source and binary archives for versions 4.0.0-alpha-1, 3.0.0, and 2.1.6; the project identifies 4.0.0-alpha-1 as alpha and says alpha or beta releases are not production ready. General questions can go to the user mailing list, while the dev list serves contributor discussions. An interactive tour teaches the Java API through exercises and is designed for Accumulo 2.1.x or greater.

Baidu Tera is a free, self-hosted distributed NoSQL database for real-time applications. It stores sparse, multidimensional tables indexed by row key, column key and timestamp, with the project describing scale to petabytes across thousands of commodity servers. Tera supports strict consistency, MVCC, automatic failover, online schema changes and snapshots. Configurable automatic sharding can use ranged or hashed strategies, with linear and modular scalability. Storage options include RAMDISK, SSD and disk tables, plus tiered and block caches and Bloom Filters for real-time queries. Applications can connect through C++, Java, Python and REST APIs. Its architecture includes an SDK, master and tablet servers using an enhanced LevelDB engine. Deployment can use raw machines or Docker, with pseudo-distributed operation on one host. The repository lists BSD-3-Clause and Apache-2.0 licenses.