To update an existing document you must specify the current revision number within the _rev parameter. For example:

PUT http://couchdb:5984/recipes/FishStew
Content-Type: application/json

{
  "_rev" : "1-9c65296036141e575d32ba9c034dd3ee",
  "servings" : 4,
  "subtitle" : "Delicious with fresh salad",
  "title" : "Fish Stew"
}

Alternatively, you can supply the current revision number in the If-Match HTTP header of the request. For example:

PUT http://couchdb:5984/recipes/FishStew
If-Match: 2-d953b18035b76f2a5b1d1d93f25d3aea
Content-Type: application/json

{
   "servings" : 4,
   "subtitle" : "Delicious with fresh salad",
   "title" : "Fish Stew"
}

The JSON returned will include the updated revision number:

{
   "id" : "FishStew99",
   "ok" : true,
   "rev" : "2-d953b18035b76f2a5b1d1d93f25d3aea"
}

For information on batched writes, which can provide improved performance, see Section 6.1.2, “Batch Mode Writes”.