Plan a database migration without downtime

Prompt for a migration plan in reversible steps that keeps the application running and checks every step. Paste it into an AI tool of your choice, which then writes the plan.

Topic: Coding & agents
Type: Prompt
Level: Advanced
Time: about 10 min

Results depend on the tool, the model and what you enter.

Result preview

Example: written by our editors, not real AI output.

Goal: rename column "customer_name" to "display_name" without downtime. 1. Expand: add new column display_name (nullable). Way back: drop the column. 2. Code writes to both columns. Way back: deploy the old version. 3. Copy data in batches of 10,000 rows. Check: rows without a value = 0. 4. Code reads only display_name. 5. After a week without errors: remove the old column. Not reversible, take a backup first. Assumption: the table has a primary key for batching.

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ChangeWhat should change in the schema?

DatabaseWhich system?

Table sizeRoughly how many rows?

Your prompt

Plan a database migration without downtime.
Change: [Change]
Database: [Database]
Size of the affected table: [Table size]
Structure: 1. Steps in the order expand, copy data, switch code, remove the old part, each with an SQL sketch. 2. For each step: can it be undone, and how? 3. How old and new code versions work at the same time during the switch. 4. How large amounts of data are moved in batches without locking tables for long. 5. Checks before and after each step, such as row counts or samples. Mark assumptions about my system as assumptions. Name commands that can cause locks in [Database].

Take particular care to plan only reversible steps and label assumptions about the system openly.

Before you answer, check: Are all instructions met? If key information is missing or a placeholder in square brackets is still in the text, ask instead of guessing. Mark assumptions as assumptions.

This is an instruction for an AI, not the result itself.

Where this prompt works

These AI tools are a good fit for this prompt:

How to use it

Fill in the fields or tap a suggestion. Leave out names, addresses and other personal data.
Copy the finished prompt into an AI tool of your choice.
Try the plan on a copy with a realistic amount of data first and measure how long each step takes.

Why does this work?

The fixed order of expanding first and removing later keeps old and new code versions working. Asking for the way back at every step prevents one-way streets.

Tips

Take a verified backup before every migration and test the restore. The plan does not replace the documentation for your database version.

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Plan a database migration without downtime

Result preview

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