DDLBuilder Docs

English

中文
日本語

English

中文
日本語

Appearance

Change Diff and Rollback ​

This guide explains how to use DDLBuilder's Visual Schema Diffing, Forward ALTER Generation, Atomic Rollback DDL, and Version Timeline Replay to manage safe database migrations.

Overview ​

Safely iterate on established production tables by reviewing visual schema diffs, generating forward migration scripts, and preparing rollback contingency plans before deployment.

Operations Walkthrough ​

1. Triggering and Inspecting Schema Diffs ​

  1. Load an existing table from the "Saved Tables" drawer.
  2. Apply changes in the workspace (add/remove columns, modify data types, or reconfigure indexes).
  3. The table header will automatically display the View Schema Changes button.
  4. Click the button to inspect structured diffs across Table Options, Columns (with rename detection and attribute diffs), and Indexes.

2. Exporting ALTER Scripts and Rollback DDL ​

  • Forward Migration: Click Copy ALTER Script in the diff modal to export DDL for production change tickets.
  • Contingency Rollback: Expand the rollback section and click Copy Rollback Script to obtain reverse DDL that safely undoes all applied changes.

3. Version History and Rollback ​

  • Open the "Saved Tables" drawer and click Version History from a table card's menu.
  • Browse all recorded historical snapshots, timestamps, and modification summaries.
  • Select any past version and click Rollback to This Version to restore the workspace instantly.

4. Schema Evolution Timeline Replay ​

  • In the Version History modal, click Timeline Replay.
  • The interactive player animates the sequential evolution of the schema from its initial version to the latest snapshot, perfect for architecture demos and team reviews.

Verification Checklist ​

  • [ ] The visual diff accurately reflects all intended changes, including detected renames.
  • [ ] The exported ALTER script matches your production database version syntax.
  • [ ] A matching rollback script is archived for change management safety.
  • [ ] Past versions can be audited and restored from the history drawer.

Tips and Common Traps ​

Production Data Compatibility

Generated ALTER and rollback scripts operate on structural DDL. If your changes introduce non-null columns without defaults or truncate data types, evaluate existing row data compatibility before execution.

  • Diff Button Visibility: The diff button only appears when an established Saved Table is modified. Scratchpad drafts have no baseline and will not trigger diffing.
  • Snapshot Retention: Saving updates appends a new snapshot to the history ledger. Create named tables at major feature milestones to preserve clear audit trails.