Cassandra vs Riak [closed]_问答_开发者_运维开发者技术经验分享

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I am looking for an eventually consistent data store and it looks like it may be coming down to Riak or Cassandra. Has anyone got expereinces of a view on this?

As you probably know, they are both architecturally strongly influenced by Dynamo (eventually consistent, no single points of failure, etc). Both also go beyond Dynamo in providing a "richer than pure K/V" data model -- in Cassandra's case, providing a Bigtable-like ColumnFamily mode, in Riak's, a Document-oriented one. I have seen sane people choose both.

I believe points that favor Cassandra include

speed
support for clusters spanning multiple data centers
big names using it (digg, twitter, facebook, webex, ... -- http://n2.nabble.com/Cassandra-users-survey-tp4040068p4040393.html)

Points that favor Riak include

map/reduce support out of the box

/Cassandra dev, fwiw

Riak is used by

Mozilla Foundation
Ask.com sponsored listings
Comcast
Citigroup
Bet365

I think they both pass the test of credible reference customers/users.

Cassandra seems more mature, and is currently doing better in benchmarks. Riak seems easier to add a node to as your cluster grows.

For completeness: A good (probably biased) comparison between the two can be found at http://docs.basho.com/riak/1.3.2/references/appendices/comparisons/Riak-Compared-to-Cassandra/

Use and download are different. Best to get references.

Perhaps a private conversation could be had where Riak references in these companies could be shared? Not sure how to get such with Cassandra, but there is a community of companies that support Cassandra that seem like a good place to start. As these probably have community participants in Cassandra development, it may be a REALLY reasonable place to start.

I would like to hear Riak's answer to recent and large deployments where customers are happy.

I also would like to see the roadmap for each product. Cassandra is a bit easier to track (http://wiki.apache.org/cassandra/) than Riak in my view as Cassandra's wiki discusses limitations and things that are probably going to change going forward, but neither outline futures well. I could understand that of an open source community ... perhaps ... but I cannot for a product for which I must pay.

I also would suggest research of Cloudant, which has what appears to be a very nice layering of capabilities. It also looks like it is bringing to bear the capabilities elsewhere in Apache land. CouchDB is the Apache platform on which Cloudant is based. BUT the indexing with Lucene seems but the tip of the iceberg when it comes to where Cloudant could go. Creating and managing an index is a very systematic process, a kind of data pipeline, that could be scripted using other Apache community assets. AND capabilities like NLP also could be added through Lucene indirectly, or maybe directly into what is persisted.

It would be nice to see a proposed Cloudant roadmap, especially since the team could mine the riches of the Apache community and integrate such into Cloudant. Such probably exists as there is an operational component to the Cloudant revenue model that will require it, if for no other reason.

Another area of interest ... Cloudant's pricing model ... it is clear their revenue model is not based on software, but around service. That is quite attractive, and it seems consistent with the ecosystem surrounding Cassandra too. I don't know if the Basho folks have won over enough of the nosql community as yet ... don't see such from any buzz around their web site or product.

I like this Cloudant web page (https://cloudant.com/the-data-layer/). I was surprised to see the embedded Erlang capability ... I did not know CouchDB was written in Erlang as this seems unusual to me in the Apache community (my ignorance); CouchDB appears to be older than other nosql products I know (now) to be written in Erlang. Whatever their strategy, they at least count Amazon EC2 and Microsoft Azure as hosting partners, indicating an appreciation of Microsoft and !Microsoft worlds - all very important if properly recognizing the middleware value potential (beyond cache or hash table applications) that these types of data stores could have.

Finally, while I don't know the board well, Andy Palmer's guidance looks like it will be valuable. He can bring some guidance vis-a-vis structured data (through VoltDB) to a world that rightly or wrongly may be unfairly branded as KVP hash tables of unstructured data. The need for structure and ecosystem surrounding nosql "databases" is being recognized ... witness Google's efforts with Spanner ... KVP/little structure/need for search-ability motivated Google's investment in the Spanner space. While we all may not need something like Spanner, we probably do need an improving and robust "enterprise" management and interoperability capability in these nosql databases to make it reasonable to incorporate them into modern cloud architectures. The needed structure can come from ease of interoperability and functional richness. It can also come from new capabilities that support conversion of unstructured data to structured data (e.g. indexes, use of NLP to create structured and parsed renderings of things inside of a KVP blob, and plenty of other things that, if put into a roadmap and published, could entice and grow a user base). Cloudant looks like it has a good chance of success ... I will take a closer look at it ...

And look what I found about CouchDB ...

CouchDB comes with a suite of features, such as on-the-fly document transformation and real-time change notifications, that makes web app development a breeze. It even comes with an easy to use web administration console. You guessed it, served up directly out of CouchDB! We care a lot about distributed scaling. CouchDB is highly available and partition tolerant, but is also eventually consistent. And we care a lot about your data. CouchDB has a fault-tolerant storage engine that puts the safety of your data first.