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Oracle Tips by Burleson |
Oracle Streams
Chapter 8 -
Down Streams Capture
Features and Advantages
In a Down Streams capture environment, the
source database can be a single instance database or a
multi-instance Real Application Clusters (RAC) database. The Down
Streams database can be a single instance database or a
multi-instance RAC database, regardless of whether the source
database is single instance or multi-instance.
Advantages of the Down Streams process include:
-
It uses fewer resources on the
source database.
-
When there is a scenario where
multiple source database changes are to be processed, one Down
Streams database can act as the central location for hosting the
Capture process which obtains database changes from multiple
sources.
-
At the same time, from one source
database, multiple targets can be serviced.
-
Copying redo log files to one or
more Down Streams databases provides improved protection against
data loss. For example, the redo log files at the Down Streams
database may be used for recovery of the source database in some
situations.
Disadvantages
Because the Down Streams Capture process needs
to wait for log switching of the redo log file and then subsequent
copy of archive log files from the source database to the Down
Steams database, there will be an unavoidable delay in capturing the
database changes. This delay may not be acceptable for some
situations.
The Down Streams capture configuration also
requires an intermediate host as well as the database system, which
is an additional expense that must be considered.
The above text is
an excerpt from:
Oracle Streams
High Speed Replication and Data
Sharing
ISBN 0-9745993-5-2
by Madhu Tumma
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