Apache AsterixDB vs Apache CouchDB

Apache AsterixDB is a free, open source, self-managed Big Data Management System for ingesting, storing, indexing, querying and analyzing data. Its Asterix Data Model extends JSON with object-database concepts, while SQL++ and AQL provide declarative queries for semistructured information. Partitioned LSM-based storage supports B+ tree, R-tree and inverted keyword secondary indexes. External datasets can be queried without loading everything into AsterixDB, using adapters for HDFS and local filesystems. Continuous feeds can ingest sources such as Twitter, RSS and sockets. The HTTP query API accepts SQL++ and can return immediate, deferred or asynchronous results. Installation options include NCService, Ansible and Amazon Web Services. The Hyracks parallel runtime has been scale-tested on up to 1000+ cores and 500+ disks. Documentation describes basic transactional concurrency and recovery, and identifies web data warehousing and social data analysis as suitable uses.

Apache CouchDB is a free document database that stores named documents and lets applications read and update them through a RESTful HTTP API. Documents can contain fields and binary attachments without following a fixed schema. Its query engine supports views made with JavaScript map functions and optional reduce functions. Incremental replication synchronizes databases in both directions between peers, including after disconnections; the project describes this as useful for offline-first applications across servers, phones, and browsers. PouchDB can replicate with CouchDB from mobile devices and web browsers. A cluster can present one logical database across multiple servers or virtual machines for added capacity and high availability. CouchDB uses an append-only file design, and its documentation describes document updates as ACID and all-or-nothing. Security features include administrator accounts, basic and cookie authentication, reader access controls, and JavaScript validation of document updates. Replicas may retain conflicting revisions for manual or automated resolution. CouchDB is self-hosted on servers or virtual machines, as a single node or cluster, and is licensed under Apache License 2.0.