spreading.
BaseX
BaseX was started by Christian Grün at the University of Konstanz in 2005
and was subsequently released using a BSD license in 2007. It is a simple,
lightweight database that does not support a lot of features but could be just
right for specific applications. Rather than using JSON, like CouchDB and
MongoDB, BaseX is designed to store document objects in XML. It supports
standard XML tools like XPath and XQuery and also includes a lightweight
GUI.
BaseX creates indexes and supports W3C recommendations and standards,
ACID-safe transactions, large documents, and various APIs like REST/JAX-
RX and XML:DB. Although not as sexy or well known as other options in
this section, perhaps because of the newness and popularity of JSON over
XML, BaseX is respected and used by many universities and enterprises.
Wide Column Stores
Wide column stores are often referred to as big table stores, after one of the
best-known examples, Google’s BigTable. Typically, a relational database
reads data from tables using rows. Data is then sorted to find only those
contents of a row that are needed. Wide column stores change the system by
reading data from tables in columns, selecting the attributes first before
reading in data. This is more efficient for input and output read-only queries.
Wide column stores therefore tend to be very efficient for databases that are
mostly used for reading stored data, especially from very large data sets.
Wide column stores use something like tables, with a defined schema for each
table. Unlike relational databases, wide column stores do not record
relationships between tables. These are not relational databases but are more
like maps that show where data exists across multiple dimensions. They are
designed for scalability and as distributed systems.
Two examples of wide column stores are discussed here. One more,
Cassandra, was discussed earlier in this chapter and fits into both this
category and the earlier key/value stores category.
BigTable
BigTable is a proprietary Google product that is used only by Google. It is