How do you back up and restore a CouchDB database?

CouchDB does not have a dedicated backup command like mysqldump. The recommended backup approaches depend on your deployment type and RPO requirements:

1. Replication-based backup (recommended for live systems) — replicate the database to a dedicated backup CouchDB instance (local or remote). Because CouchDB replication is idempotent and incremental, subsequent backup runs only copy changed documents. Schedule it via the _replicator database or a cron job calling /_replicate.

# One-shot backup to a backup server
curl -X POST http://admin:pass@localhost:5984/_replicate \
  -H "Content-Type: application/json" \
  -d '{
    "source": "http://localhost:5984/production_db",
    "target": "http://backup:5984/production_db_backup_2024_03",
    "create_target": true
  }'

2. File-system snapshot — stop CouchDB (or freeze I/O via OS-level snapshot), copy the .couch database files from the data directory (/var/lib/couchdb/ on Linux), then restart. Simple but requires downtime or snapshot coordination.

3. couchdb-backup / couchdbdump tools — community tools like couchdb-backup or couchdbdump serialize all documents to a JSON/ndjson file using the _all_docs or _changes endpoint.

# Dump all documents to ndjson using the _all_docs feed
curl "http://admin:pass@localhost:5984/mydb/_all_docs?include_docs=true" \
  | python3 -c "import sys,json; [print(json.dumps(r['doc'])) for r in json.load(sys.stdin)['rows'] if not r['id'].startswith('_design')]" \
  > mydb_backup_$(date +%F).ndjson

# Restore by posting each line to _bulk_docs
jq -sc '{docs:.}' mydb_backup_2024-03-15.ndjson | \
  curl -X POST http://admin:pass@localhost:5984/mydb_restore/_bulk_docs \
  -H "Content-Type: application/json" -d @-

For clustered deployments, replicate per-database since there is no single database file to snapshot. Always verify backups by doing a test restore periodically.