Imagine in a project you need to pull data in near real time from variety of different databases into a single database. For this you can use a tool named Oracle Golden Gate.
It can pull data from the following databases in real time
- Oracle Of course :)
- IBM DB2
- Microsoft SQL Server
When the source is Oracle database, the data can be pulled in near real time from the Online redo log files itself, without reading the actual DB files. Therefore this does not impact the performance of system because Golden Gate does not rely on relational structures for pulling data out of Oracle. Not only that, you can perform a by directional synch of data as well, i.e. from Source to Target, and changes from Target applied to Source.
It must be noted that there are some limitations in Golden Gate when it runs against a RAC Database. Goldengate can extra runs against only one single instance of database in RAC.
For detailed documentation, please read this PDF