The migration
of
this two databases may lead to damage the system design. In the real system, application interface by relational database with the help of SQL. At same period of time to use both the databases the application design need to be changed. At the time of integrating
real system to NoSQL database, a mechanism is to be needed for data
migration from relational to NoSQL.
Relational database is the most widely used data storage technology for many years. In today’s world requirement for data processing have prompted emergence of new data storage, retrieval and processing mechanism. One of such mechanism is NoSQL
databases is
also
called non-relational databases.
NoSQL databases is one of the mechanisms, and is called as non-relational
databases. Numerous companies sift to NoSQL
database and
utilize
it
for
storing
and managing data and
relational database system must be migrated to NoSQL. Due to
the
difference in the schema of NoSQL database and relational
databases, user
have to learn a
new database. As the join operation
is not supported in the NoSQL, user have to collect
the
data from
different table and leads to a poor performance. So the
schema
conversion is must
for
the
migration to relational to NoSQL.
Designed NoSQL is termed as ‘Not Only SQL’ for distributed data store. To overcome the limitations of RDBMSs in storing and processing cloud big data, NoSQL databases
have been developed for large scale and high
concurrency
applications. Web 2.0 applications needs large data storage with
flexible schema
for
attributes such as picture, video,
text, comments, and other information,
the
NoSQL databases are mainly designed to comply with the requirements of Web 2.0
applications. Key features of NoSQL
databases
includes: 1.
Ability to scale horizontally. 2. Ability to partition or distribute over many functions 3. Comparably weaker concurrency
than ACID. 4. Compared to SQL binding, simple call level protocol.
5. Ability to attach new
feature to data
records dynamically. 6. Capable use of RAM and distributed indexes for data storage.
Horizontal scaling, replication and distribution of data over
various purpose make data reading and writing operations
becomes
faster. ACID properties which are essential for data
consistency for the parallel transaction, but NoSQL does not
offer the ACID properties. In the distributed environment
the
main requirement is system scalability. The web based
applications mainly run
on such
distributed
environment.
And
for a distributed system
it is not possible to ensure simultaneous Consistency, Availability and Partition tolerance at the same which is stated as the CAP theorem that articulates two of them can be achieved. A weaker model BASE (Basically
Available, Soft state, Eventual consistency)
replaces ACID in
order to keep NoSQL data consistent and reliable. Invented by Eric Brewer and according to BASE properties
are
described as: Basic availability: Any request will be responded with successful
or failed execution. Soft state: The state of the
system is ‘soft’ which may change over time. So due to eventual consistency
changes even may be going on without any input. Eventual consistency: Eventually the database will be
consistent even though it could be inconsistent momentarily.
Five categories of NoSQL databases are: column-oriented,
Document –oriented, key-value, graph, multi-model. The most
important types of databases for some years is key-value
store and document
databases. In proposed model we concentrate
NoSQL database as document-oriented database.
