Free · Lesson 2 of 11
DMS has a premigration assessment on a task, a schema conversion assessment inside DMS Schema Conversion, and the older AWS Schema Conversion Tool. They are three reports. Mixing the names is how a project skips the wrong work.
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One checklist asks whether the moving truck can get out of the driveway. Another checklist asks whether the furniture will fit in the new house. A desktop app can write that second checklist too. They are not the same clipboard.
A premigration assessment runs against a replication task. It looks for DMS prerequisites: supplemental logging, primary keys, unsupported data types, LOB settings, and similar task blockers. It does not convert a stored procedure from one database language to another.
Read the assessment before the first full load, and again if you change table mappings. A green assessment is not a green cutover.
The AWS Schema Conversion Tool is a desktop application you install. It assesses and converts schema and database code for heterogeneous moves. It is not a replication task and it is not installed by creating a DMS endpoint.
DMS Schema Conversion is a feature in the DMS console. AWS describes it as built on the SCT conversion engine, and as serverless in the sense that a migration project provisions its own resources. You do not manage that project as a replication instance. It can write a conversion assessment that counts what converts automatically and what needs a person.
That conversion report is still not the premigration assessment. One is about schema and code. The other is about whether a DMS task can run.
| Report | Asks | Does not ask |
|---|---|---|
| Premigration assessment | Can this DMS task run? | Whether PL/SQL became PL/pgSQL |
| DMS Schema Conversion assessment | What schema and code convert? | Whether the replication instance is large enough |
| AWS SCT assessment | A desktop view of conversion work | It is not a serverless DMS task |
Supported pairs for data movement and supported pairs for schema conversion overlap and are not identical. AWS has added generative AI help for some conversion paths and not others. The console and the current user guide are the list. This course will not freeze a matrix that the next service update would make wrong.
Step 1 of 3The premigration assessment belongs to the replication task.
Step 2 of 3DMS Schema Conversion reports what it can translate.
Step 3 of 3AWS SCT is the installable application. Related engine, different product.
For each line, write task, schema, or neither. The answers are in the comments.
Supplemental logging is off on Oracle. # task
A procedure uses a built-in the target lacks. # schema
The security group blocks port 5432. # neither — that is the network lesson
Fifty tables have no primary key. # task, and it also hurts CDC
Checked against the linked documentation in October 2026. A later release can move a flag, a price, or a supported pair. Use the page for the version you installed.