Checkpoints[05]

PouchDB allows users to enable or disable replication checkpoints (which would be modified based on system performance goals and/or usage), which are used for synchronization across the local and remote servers.

Compression[06]

PouchDB doesn't currently support compression by default, however there is a plugin (Transform Pouch) that allows for compression of data.

Concurrency Control

PouchDB's concurrency control policy is multi-version concurrency control, allowing consistency of reads.

Data Model[07][08]

PouchDB uses an unstructured document data model, where documents are JSON serializable. It also supports attachments, which store binary data.

Foreign Keys[09]

Indexes[10]

Starting with version 2.2.0, PouchDB supports secondary indexes using B-trees. It supports an ID-based index by default.

Isolation Levels

Joins[11]

PouchDB does not support joins since it uses a document-based data model. To mimic the existence of joins, the Relational Pouch plugin can be used. It enables PouchDB interaction as if it were a relational database. Regardless, the joins used here are actually created by additional requests (instead of classic join algorithms).

Logging[12][13]

PouchDB doesn't support logging itself, however different types of logging are used by its various backends. For LevelDB-backed PouchDB (for Node.js adaption), LevelDB which uses logical logging.

Query Execution

PouchDB can use map/reduce or create MangoQueries (used to build secondary indexes). Users can create an empty query to speed up the query. By dividing into map and reduce, parallelism can speed up the process.

Query Interface[14]

PouchDB utilizes a custom API (both a Javascript API and an HTTP API) for its query interface. As it is designed for web browsers, this API supports callbacks, promises, and async functions.

Storage Organization[15][16]

When offline, data is stored locally using WebSQL (deprecated) or IndexedDB, depending on the browser. For IndexedDB usage, the method of storage organization is ISAM. When online, data synchs with CouchDB (and other servers). CouchDB storage uses copy-on-write to update database files.

Stored Procedures[09]

PouchDB allows for stored procedures by using view functions in JavaScript.

Views[17][18]

PouchDB supports both materialized (persistent) views as well as virtual (temporary) views. In PouchDB, views are synonymous with indexes (i.e. the same as CREATE INDEX in SQL-based databases). Views store information about a specified (map/reduce) query. In turn, views are stored in design documents. These views are very similar to CouchDB however PouchDB uses ASCII ordering to order view query keys. It also does not support the offset property that CouchDB does. Instead, a skip parameter is used instead of an actual offset.