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3.7 Real-Time Database Replication
3.7
Real-Time Database Replication
By running multiple RTI Real-Time Connect daemons on different nodes connected to
different databases, and configuring all of the daemons to publish and subscribe to the
same table, changes made by applications to a table on one node can be automatically
replicated to tables on all of the other nodes. Figure 3.7 shows how RTI Real-Time Connect can be used to perform lazy table replication between distributed databases.
With lazy replication, an update is sent to the subscribers after the transaction is committed into the local database. The advantages of lazy replication are short response
time and high concurrency, since locks in the data cache are immediately released after a
transaction commits and before it is sent on the network.
Figure 3.7
Replicating Tables Across Databases
User App
(SQL)
User App
(SQL)
User App
(SQL)
SQL
SQL
RTI Real-Time Connect
Daemon
Relational
Database
Table.Tracks
Flt Lat. Long.
---------------------C129 34.5 102.3
C054 27.7 46.8
…
…
3. Architecture
User App
(SQL)
SQL
Table.Passengers
Flt Name Addrs
---------------------C129 A. Johnson …
C054 J. Smith ….
…
…
Enterprise
RTI Real-Time Connect
Daemon
SQL
Relational
Database
Table.Tracks
Flt Lat. Long.
---------------------C129 34.5 102.3
C054 27.7 46.8
…
…
Table.Passengers
Flt Name Addrs
---------------------C129 A. Johnson …
C054 J. Smith ….
…
…
Enterprise
By setting different QoSs for the DDS publications and subscriptions created by the RTI
Real-Time Connect Daemon, features such as remote table initialization and application
timestamp-based conflict resolution are enabled. RTI Real-Time Connect provides an initialization attribute that automatically sets the QoS values associated with database replication.
Even different DBMSs can be synchronized by the RTI Real-Time Connect Daemon with
table changes in Oracle TimesTen In-Memory databases propagated to corresponding
tables in Oracle 11g or MySQL 5.1 databases, and vice versa.
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