CouchDB Cheat Sheet

CouchDB's HTTP API, document revisions, map/reduce views, and built-in replication model for offline-first JSON document storage.

2 PagesIntermediateMar 10, 2026

HTTP API Basics

Managing databases and documents with curl.

bash

# Create a databasecurl -X PUT http://localhost:5984/mydb# Create a documentcurl -X POST http://localhost:5984/mydb \  -H "Content-Type: application/json" \  -d '{"name": "Alice", "email": "a@b.com"}'# Get a documentcurl http://localhost:5984/mydb/<doc_id># Update requires the current _revcurl -X PUT http://localhost:5984/mydb/<doc_id> \  -d '{"_rev": "1-abc123", "name": "Alice2"}'

Views (Map/Reduce)

Querying data with a design document.

javascript

// Design document defining a view{  "_id": "_design/users",  "views": {    "by_email": {      "map": "function (doc) { if (doc.email) { emit(doc.email, doc); } }"    }  }}// Query it: GET /mydb/_design/users/_view/by_email?key="a@b.com"

Core Concepts

How CouchDB stores and syncs documents.

Document- a JSON object with a unique _id and a system-managed _rev
_rev- revision token used for MVCC-based conflict detection on every update
Design document- a special document (_id starts with _design/) that holds views
MVCC- CouchDB never overwrites data in place; every update creates a new revision
Replication- built-in, bidirectional, works over plain HTTP for offline-first sync
_changes feed- a stream of document changes used to drive replication

Pro Tip

Always send the current _rev when updating or deleting a document — CouchDB rejects writes carrying a stale _rev, which is how it surfaces conflicts instead of silently overwriting concurrent edits.

Was this cheat sheet helpful?

Neo4j (Graph Database) Cheat Sheet

MariaDB Cheat Sheet