Hey, everyone.
And welcome back.
Now, in today's video, we are going to discuss about the migration types in DMS.
Now, whenever you are migrating the data through DMS from source to destination, there are multiple
set of options for migrations that the DMS provides.
For example, you have one time migration, you have continuous replicating, data changes, etc. For
example, let's say you want to there is some existing data in the on premise database and you want
to migrate it to IDs.
So this would be one time migration.
Now whatever new data that is being added at the on premise database level after the migration is completed
will not be migrated back to IDs in a one time migration stage.
However, if you want that, whatever new data that is being added at the on premise database level
also needs to be replicated.
This is also the option that the DMS provides.
So at a high level overview, there are three primary options as part of migration.
First one is migrating the existing data.
This is very simple to understand where you perform one time migration from source endpoint to the target
endpoint.
That's about it.
After this migration is completed, whatever new data that is being added at the source database will
not be replicated to the target database.
Second option is migrate the existing data and replicate ongoing changes.
So in here, the one time migration remains to be the same and after the one time migration there is
also a continue replicating data changes from source to target.
So whatever new data that gets added to the source database will also be replicated to the target database.
And the third one is the replicate data changes only in here.
The one time migration is not performed, but here it continues to replicate data changes from source
to target.
So depending upon the use case of the organizations, you will generally use one of these.
Now, in fact, let me also quickly show you this on.
Where do you see the options?
Now, whenever you create a database migration task in the migration type, you have three types migrate
existing data, migrate existing data and replicate ongoing changes and replicate data changes only.
All right.
So make sure to choose the right set of options based on the requirements.
Now, before we conclude, a few important points to note.
First one is that most engines require some additional configuration to make it possible for the capture
process to consume change data in a meaningful way without the data loss.
For example, if you're making use of the Oracle, it requires the addition of supplemental logging
and MySQL requires binary logging.
If you do not really have the binary logging enabled.
And then if you select the second option for an example, migrating existing data and replicating ongoing
changes.
So in such cases, the DMS will give you an error.
Now before we conclude, few more pointers to note, as we know that you can create a task that captures
the ongoing changes after you complete the initial migration.
So this specific approach is also called as the ongoing replication or change data capture or CDC.
So sometimes in exams, if they say CDC, you should know that it is nothing but the ongoing replication
where the new updates in the source is also reflected in the target database.
So that's the high level overview.
And with this will conclude today's video.