This is a post in a series about the Apache CouchDB 3.0 release. Check out the other posts in this series.

Apache CouchDB 3.0 comes equipped with a new partitioned database feature, offering  more performant, scalable, and efficient querying of secondary indexes.

Users decide, at database creation time, whether or not to create the database with partitions. All documents in a partitioned database require a partition key, and all documents within a partition are grouped together. Common partition keys could include usernames, IoT device IDs, or locations. Partitioned database documents also have an _id field, but the _id field is in two parts, the partition key and the document key, separated by a “:” character:

Querying against a secondary index for a partition scans only the specified partition range within a single shard.  Compared against a “global” query that requires collating the results of reading a copy of every shard, partition queries require much fewer resources and respond faster at scale. To visualize the difference in database operations, compare a global query on left with a partition query on right:

Querying a partitioned database with a partition key can be done against the Primary Index (_all_docs), as well as a MapReduce view, Search (now available in Apache CouchDB 3.0), or Mango index. Users can combine both partitioned and global indexes within the same database to meet their querying requirements. 

For more information on leveraging Partitioned Databases in Apache CouchDB, check out the following resources: 

• Apache CouchDB Reference Guide: Partitioned Databases (requires switch to stable URL) for an overview of the feature, how to create partitioned databases, and an example data model.
• Apache CouchDB API Reference: Partitioned Databases (requires switch to stable URL) for API details on querying against a partition. 
• A four-part series on the IBM Cloudant blog around Partitioned Databases applicable to Apache CouchDB users:
  • Introduction
  • Data Design
  • Data Migration
  • Sizing

This is a post in a series about the Apache CouchDB 3.0 release. Check out the other posts in this series.

CouchDB has always relied on Mozilla’s JavaScript engine, Spidermonkey, for all its JavaScript needs. However, being a web browser engine, the development of Spidermonkey is many times faster than that of CouchDB, and at one point, it got rewritten from C to C++. This made our custom bindings obsolete.

And because updating custom bindings from C to C++ is neither easy, nor fun, CouchDB kept staying dependent on the now very ancient Spidermonkey version 1.8.5. The implications were as far reaching as various package managers keeping that version around just for CouchDB.

While there is nothing inherently wrong with Spidermonkey 1.8.5, JavaScript has seen a surge of changes in the past decade, and those changes are now finally available in CouchDB 3.0 and Spidermonkey 60, most notably:

• ECMAScript 6 support
• Multi-generational leap in JavaScript execution performance

Users have been asking for an update in this area for a long time, and we are happy to announce that it is finally here.
Special thanks to Peng Hui Jiang, who took the time to make this technically challenging update possible.