---
title: What Schema Conversion Will Not Rewrite
description: DMS Schema Conversion sorts objects into converted, warnings, and will-not-convert. The project is the last bucket plus the SQL that lives in the ORM. A connection-string change is not that backlog.
url: https://www.bravelo.co/blog/schema-conversion-residue-stored-procedures-orm/
datePublished: 2026-11-03T00:00:00.000Z
dateModified: 2026-11-03T00:00:00.000Z
author: palaniappan-p
category: Cloud Architecture
tags: aws, aws-dms, amazon-aurora, database-migration
---

# What Schema Conversion Will Not Rewrite

> DMS Schema Conversion sorts objects into converted, warnings, and will-not-convert. The project is the last bucket plus the SQL that lives in the ORM. A connection-string change is not that backlog.

The [DMS playbook](https://www.bravelo.co/blog/aws-database-migration-dms-aurora-playbook-2026/) tells you to run an assessment and then says it does not cover ORM rewrites beyond what that assessment flags. The refactor post's database pattern is still easy to misread as a connection-string change. On 4 October 2026 the useful unit is the assessment itself: DMS Schema Conversion, not the older Schema Conversion Tool name.

The [Oracle and SQL Server decision](https://www.bravelo.co/blog/oracle-sql-server-to-aurora-postgresql-decision/) owns the fork: stay licensed, Babelfish, or convert. This page starts only after convert is the choice. Babelfish is partial T-SQL. It is not a zero-rewrite promise, and it is not this backlog.

> **Reproduce this:** Copy the [assessment buckets](https://www.bravelo.co/examples/architecture-blog-2026/schema-conversion-residue/assessment-buckets.md). Four counts, from one assessment report. Staff the third and fourth before anyone says cutover.

## Four buckets

| Bucket | What it is | What you do |
| --- | --- | --- |
| Auto-converted | Objects the assessment converts cleanly | Do not staff a project around this count. |
| Warnings | Converted with a behavior you have not accepted | Read them. A warning is not a percentage. |
| Will not convert | Procedures, triggers, jobs, and types the tool refuses | This is a backlog with owners. |
| Application SQL | Statements in the ORM or the service, invisible to the database assessment | Search the code. The assessment will not list them. |

We recommend staffing the third and fourth buckets before cutover. The trade-off is a longer project than the row-count demo. A weekend cutover that moves tables and leaves procedures behind is how the application fails on Monday with the data already on Aurora PostgreSQL.

## Where this fails

> **What broke:** Lab, 4 October 2026. Not a customer account. The plan quoted the auto-converted object count and scheduled cutover. The will-not-convert list still included the job that calculated the nightly balance. Detection: buckets three and four were blank on the sheet. Recovery: stop the cutover date until those two lists have owners. Lesson: DMS moving rows is not the application running.

## What to do this week

1. Open the latest DMS Schema Conversion assessment. Fill the four counts.
2. Turn will-not-convert into tickets. Do not average them into a percent complete.
3. Search the application for vendor SQL the assessment cannot see.
4. Leave task settings, LOB lag, and the cutover checklist on the [DMS playbook](https://www.bravelo.co/blog/aws-database-migration-dms-aurora-playbook-2026/).
5. If the residue is the engagement, talk to [RDS consulting](https://www.bravelo.co/services/aws-rds-consulting/).

## What this post doesn't cover

It does not choose Babelfish versus convert, design Aurora Limitless, or walk DMS task settings. It does not claim a percentage of objects that convert. That number is whatever your assessment says.

## FAQ

### Why does the application fail after DMS moves the data?
Because the assessment's will-not-convert objects, and the SQL that lives in the application rather than the database, were not staffed. Auto-converted tables moving rows is the part DMS does. Procedures, triggers, agent jobs, and vendor SQL in an ORM are the residue.

### When should we not schedule cutover?
Do not schedule cutover while the will-not-convert bucket and the application-SQL bucket are unread. Those two are the backlog. The auto-converted count is not evidence that the application will run.

### What could go wrong if we treat warnings as noise?
A warning is a behavior you have not accepted. Shipping it as converted means the first production path that hits that object fails after the data is already on Aurora. Read warnings as a list, not as a percentage.

### Is this the Oracle and SQL Server decision?
No. That article chooses stay licensed, Babelfish, or convert to Aurora PostgreSQL. This article starts after convert is the choice, and it reads the assessment. The DMS playbook still owns task settings and the cutover weekend.

### Should we still say Schema Conversion Tool?
No. The current product name is DMS Schema Conversion. Older posts say SCT. Do not open a third name in the plan.

---

*Source: https://www.bravelo.co/blog/schema-conversion-residue-stored-procedures-orm/*