Databases Reference
In-Depth Information
their projects. In spite of all that power and money, they eventually realized that a rela-
tional model wouldn't meet their future business needs.
Many in the NoSQL community cite Amazon's Dynamo paper as a significant turn-
ing point in the movement. At a time when relational models were still used, it chal-
lenged the status quo and current best practices. Amazon found that because key-
value stores had a simple interface, it was easier to replicate the data and more reli-
able. In the end, Amazon used a key-value store to build a turnkey system that was reli-
able, extensible, and able to support their 24/7 business model, making them one of
the most successful online retailers in the world.
1.3.5
Case study: MarkLogic
In 2001 a group of engineers in the San Francisco Bay Area with experience in docu-
ment search formed a company that focused on managing large collections of
XML
documents. Because
XML
documents contained
markup
, they named the company
MarkLogic
.
MarkLogic defined two types of nodes in a cluster: query and document nodes.
Query nodes
receive query requests and coordinate all activities associated with execut-
ing a query.
Document nodes
contain
XML
documents and are responsible for executing
queries on the documents in the local filesystem.
Query requests are sent to a query node, which distributes queries to each remote
server that contains indexed
XML
documents. All document matches are returned to
the query node. When all document nodes have responded, the query result is then
returned.
The MarkLogic architecture, moving queries to documents rather than moving
documents to the query server, allowed them to achieve linear scalability with peta-
bytes of documents.
MarkLogic found a demand for their products in US federal government systems
that stored terabytes of intelligence information and large publishing entities that
wanted to store and search their
XML
documents. Since 2001, MarkLogic has matured
into a general-purpose highly scalable document store with support for
ACID
transac-
tions and fine-grained, role-based access control. Initially, the primary language of
MarkLogic developers was XQuery paired with
REST
; newer versions support Java as
well as other language interfaces.
MarkLogic is a commercial product that requires a software license for any data-
sets over 40
GB
. NoSQL is associated with commercial as well as open source products
that provide innovative solutions to business problems.
1.3.6
Applying your knowledge
To demonstrate how the concepts in this topic can be applied, we introduce you to
Sally Solutions. Sally is a solution architect at a large organization that has many busi-
ness units. Business units that have information management issues are assigned a
solution architect to help them select the best solution to their information challenge.
