Database replication SQL server

1
An Introduction to Database Replication

• The volumes of data generated by businesses today
  are massive. IT departments are expected to
  ensure that this data is online and accessible
  indefinitely, thereby putting immense pressure on
  the data management process. The need then is to
  replace outdated and inefficient legacy processes
  through agile and new techniques. SQL Server
  Replication is the most used technique to achieve
  this goal.

2

• But first what is SQL Server Replication? It is
  a technology for copying and distributing objects
  from one database to another after which the
  databases are synchronized to maintain integrity
  and consistency of data. Database replication SQL
  server is used for continuous copying and
  synchronizing data or scheduled to run at
  intervals that are determined from time to time.
  The data synchronization can be carried out in
  several ways as per the replication techniques
  deployed. 

3

• Here are some of the techniques used for data
  replication. 
• Snapshot replication  In this process, a
  snapshot is taken of data on one server which
  is then moved to another server or sometimes
  another database on the same server. After the
  first synchronization snapshot, replication will
  refresh data in published tables periodically
  depending on what is preset. This technique might
  seem quite easy to set up and maintain but all
  data has to be copied each time a table is
  refreshed. Between refreshes, data on the
  publisher and subscriber might differ. 

4

• Transactional replication  It is the process of
  copying data from the publisher once to the
  subscriber and then delivering transactions to
  the subscriber (or more than one subscriber) as
  they happen on the publisher. The first copy of
  the data is transmitted through the same
  mechanism as with snapshot replication. As and
  when the publisher inserts updates or deletes
  records, the transactions are forwarded to the
  subscriber(s). 

5

• To ensure quick database replication SQL server,
  a configuration command may be generated to
  deliver transactions continuously. You can even
  run the synchronization tasks periodically. This
  form of replication works best where there is a
  dedicated and dependable line between database
  servers taking part in the replication process.
  Typically, database servers that subscribe to
  transactional publications use data strictly for
  read-only purposes without scope for
  modifications.     

6

• Merge Replication
• In this replication technique, data from
  multiple sources are combined in a single
  database. As in transactional replication,
  initial synchronization is done by taking a
  snapshot of data on the publisher and moving it
  to subscribers. However, unlike transactional
  replication, merge replication allows changes to
  be carried out on the same data on publishers and
  subscribers even though subscribers may not be
  connected to the network. Once subscribers
  connect to the network, this process will change
  data on the publisher by detecting and combining
  changes from all subscribers. Merge replication
  is useful when there is a need to modify data on
  remote computers and subscribers are not assured
  of a stable and guaranteed link to the
  network.  This in a nutshell is what database
  replication SQL server is all about.