Issues with Down Streams
However, the use of Down Streams capture is
not without its shortcomings. There is unavoidable delay in
capturing the database changes since the Down Streams Capture
process needs to wait for the log switching of the redo log file
and the subsequent copying of the archive log file from the
source database to the Down Streams database.
The Down Steams capture configuration
requires an intermediate host and the database system, which is
an additional expense. A new Oracle database instance has to be
dedicated to host the Down Streams capture.
Configuration of Down Streams Capture
The source database needs to be at least
the Oracle 10g release. At the same time, the downstream
capture database should be of the same version as that of the
The operating system on the source site and
downstream capture site must be the same, but the operating
system release does not need to be the same. For example, a
32-bit operating system is in use on the source database host,
the same 32-bit operating system must be maintained at the
downstream database host. Other hardware elements, such as the
number of CPUs, memory size, and storage configuration, can be
different between the source and downstream sites.