Recent announcements from Twitter and Digg.com underscore the growing awareness of NoSQL databases as an alternative to relational database management systems. But just what the future holds for NoSQL is an open question.
The buzz around the NoSQL movement
in the past year has grown
considerably, to the point where advocates organized a one-day conference in
just last week
to discuss its future.
from Twitter and Digg.com supporting a NoSQL approach added fuel to this
buzz, and while its ultimate growth among enterprises remains a subject of
discussion, one thing is clear-the idea of a NoSQL
database is starting to get a new level of consideration in the
Made up of a variety of
nonrelational data stores, the NoSQL movement spans open-source projects such
as Cassandra, CouchDB and MongoDB, as well as products from companies like Mark
Logic, which makes a native X M L database. While the hype around the subject
is relatively new, various NoSQL alternatives such as data grids, Google
BigTable, Amazon Dynamo and other solutions are not, and have actually been
around for years, noted Nati Shalom,
with many trends
, it's probably a convergence of trends rather the
something particular [that led to the rise of NoSQL]," Shalom said. "On the business
side, social networking has changed quite significantly our Web experience,
from read mostly Websites we're turning into heavy read/write sites like
Twitter and Facebook with lots of content driven by users rather than the site
provider. ... Under that condition, lots of common practices such as static
provisioning based on peak load and read mostly clusters started to break
completely and forced a completely different way of doing things."
In addition, the data
center landscape is changing, he added, explaining that memory resources are
now available at a greater capacity and at lower cost, and that network
bandwidth and computing power are growing as well.
question is how to take advantage of these powerful and cost-effective resources,"
Shalom told eWEEK. "The relational database, which has been the storage system
of choice for several decades, was built under the assumption that memory is
scarce and the network is a bottleneck-plus, it doesn't scale to the level
required by today's large-scale applications. Virtually every popular Web
application has found that a single relational database cannot meet its
The movement certainly has
its adherents in the Web 2.0 world. Facebook open-sourced the Cassandra database
in 2008. Since then, Digg.com has chosen the database
, and Twitter
is reportedly planning
to do the same.
"Each system has its own
strengths and weaknesses, but Cassandra has a good blend of everything," Digg's
Ian Eure noted in a September blog post
Digg's plan to switch to Cassandra. "It offers column-oriented data storage, so
you have a bit more structure than plain key/value stores. It operates in a
distributed, highly available, peer-to-peer cluster. While it's currently
lacking some core features, it gets us closer to where we want to be than the
But the growing uptake
should not be taken as an indication that SQL is dead. For one thing, NoSQL
databases lack the focus on consistency found in relational databases, trading
that instead for a focus on availability and partition tolerance.
Matt Aslett, an analyst
with The 451 Group, said that while distributed column stores like Cassandra
have found a home in some situations, it's the document-oriented databases like
MongoDB, CouchDB and Riak that hold the most promise for enterprises in the
"While there will be
isolated examples of key value and distributed column store adoption, for the
most part they are projects that have been designed to fulfill the very unique
requirements of their creators," he told eWEEK in an e-mail. "The
document-oriented databases are also differentiated from the key value and
distributed column stores in that they are the products of traditional start-up
ventures rather than user organizations. As yet there are no commercial support
providers for Cassandra, Voldemort or Tokyo Cabinet."
MongoDB was created by 10gen, CouchDB by Couchio and Riak by Basho Technologies,
all of which are traditional venture-backed startups providing support,
services and consulting, he said.
replace relational databases, Shalom sees a future where NoSQL and relational
have a happy marriage.
"Currently there are two
approaches to marry the RDBMS and NoSQL worlds," he said. "One [is] taking a
NoSQL implementation and wrapping it up with SQL fa???ade. This is where Google
as well as GigaSpaces are already providing solutions that can support standard
SQL semantics on top of a NoSQL storage. Two, taking an existing RDBMS and
making it cloud enabled. This is where SQL Azure from Microsoft and Amazon RDS
start to provide a SQL solution that has NoSQL flavor built into it."
"I see a convergence of RDBMS and NoSQL to the point where the
difference between those two models will start to blur," he said.
To Mark Logic
Dave Kellogg, one of the most
interesting facets of the NoSQL movement is that it shows innovations in the
database space are not just coming from Oracle,
"I don't think it hurt
things any that the relational database market itself had become this
comfortable oligopoly, where it really coalesced around the big three vendors. ...
I think the
... his eyes are going to open to the
realization that you don't just have to use [
] DB2, Oracle or [Microsoft] SQL
Server," Kellogg said.