nosql - Difference between CouchDB and Couchbase - Stack Overflow

nosql - Difference between CouchDB and Couchbase - Stack Overflow

Philosophy

I have never seen it directly pointed out but this may be actually the most important difference between those two databases because it is deeply about the underlying philosophy of distributed computing models and not only about certain features, APIs or licensing. CouchDB and the Couchbase Server completely differ in their philosophy of building distributed systems and databases.

According to the CAP theorem it is impossible for a distributed database to simultaneously provide consistency, availability and partition tolerance.

CouchDB is an AP type system (provides Availability and Partition tolerance).

Couchbase Server is EITHER a CP type system (according to Wikipedia) OR a CA type system (according to Couchbase technical update) - WHICH OF THESE IS CORRECT? PLEASE COMMENT.

Features

This is what I found to be a list of CouchDB features that are not supported by the Couchbase Server:

• no RESTful API (only for views, not for CRUD operations)
• no _changes feed
• no peer-to-peer replication
• no CouchApps
• no Futon (there is a different administration interface available)
• no document IDs
• no notion of databases (there are only buckets)
• no replication between a CouchDB database and Couchbase Server
• no explicit attachments (you have to store additional files as new key/value pairs)
• no HTTP API for everything (you need to use the Couchbase Server SDKs or one of the Experimental Client Libraries at Couchbase Develop so no experiments with curl and wget)
• no CouchDB API (it uses the Memcached API instead)
• you can't do everything from the browser (you have to write a server-side application)
• no two-tier architecture for Web apps is possible (you have to write a server-side application to sit between the browser and the database, like with relational databases)
• no eventual consistency
• not entirely open-source/free software
• not a drop-in replacement for CouchDB (seems like a drop-in replacement for Memcached instead)

Those features of CouchDB may or may not be important to you so whether the lack of them is a disadvantage or not is strictly subjective, but I think that the decision whether to switch from CouchDB to Couchbase Server or not should be based on those differences and your dependence on those feature in your current CouchDB deployments.

For example if you've got interested in CouchDB after watching The CouchDB changes feed NodeCamp talk by Mikeal Rogers or one of the great CouchApp tutorials by J. Chris Anderson then you have to realize that if you want to switch to the Couchbase Server then you will have to forget about pretty much everything they were talking about.

Because of that I would say that Couchbase Server looks like an evolution of Memcached and Membase (not an evolution of CouchDB) and as such it looks like a great product if you are currently using Memchached or Membase. If you are using CouchDB in the most basic way then you may consider using the Couchbase Server for the same things and it may or may not perform better (if you don't mind the license restrictions). But if you are actually using any of the features that are unique in CouchDB (like the changes feed, CouchApps, two-tier architecture, peer-to-peer replication etc.) then you can either forget about those features or stay with CouchDB. In any case make sure to read and understand the Migration to Couchbase for CouchDB Users tutorial before you think about switching.

People often get the wrong impression (maybe after reading things like "What's the future of CouchDB? It's Couchbase.") that CouchDB is somehow obsoleted by the Couchbase Server, or that it is an old, legacy version of Couchbase. Meanwhile CouchDB is an actively maintained open-source project, Couchbase server is a completely seperate project (it is a newer project but it is not a newer version of CouchDB - they are not even compatible) and since even new tools for creating CouchApps still keep being developed (eg. see the Kanso project) then CouchDB is not going anywhere soon.

I hope it clarifies the confusion. Please correct me if I'm wrong on anything here.

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