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Dbvisit Replicate and Sequences

Question

I am going to use Dbvisit Replicate. What do I need to know about sequences? Are they replicated?

Answer

This is a frequently asked question and deserves a full answer. In our example we will assume this is an Oracle database replicating to an Oracle database.

A sequence is basically a number generator in Oracle. When the sequence populates a column in Oracle the actual value is inserted into the row in the table. That value also makes it to the Oracle redo logs.

The MINE process will grab the value from the redo log. Notice how the MINE process doesn't even know (or care) that the value came from a sequence. It grabs the data and then puts the data into the PLOG. The APPLY process will read the PLOG and place the data into the target database.

The exception to this rule is if you are running bidirectional replication. There you will want to make sure that sequences are different on each side.

See http://support.dbvisit.com/hc/en-us/articles/216515107-General-bi-directional-2-way-replication-considerations for more details.

Chris Lawless Answered

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