Migrations

Schema Migration

Catch breaking schema changes before production.

Analyze DDL and schema changes for data loss, compatibility, and downstream risk.

Review schema changes before they surprise production.

The problem it solves

Schema changes can look harmless while still breaking consumers: dropped columns, type narrowing, nullability changes, renamed fields, missing defaults, or removed constraints.

What it does

Compares old and new schema definitions.
Flags breaking changes and data loss risks.
Highlights type narrowing, dropped columns, and compatibility issues.
Supports safer production migration review.

When to use it

BEFORE

applying DDL migrations

BEFORE

merging schema YAML or dbt contract changes

DURING

warehouse migrations

WHEN

reviewing pull requests that alter table shape

How it works

The skill compares the two schemas, runs migration analysis, and flags each risk with severity and why it matters.

Tools used

altimate_core_migration

Analyze migration risk through Altimate Core.

altimate_core_schema_diff

Compare schema versions through Altimate Core.

schema_diff

Compare schema changes and highlight compatibility or migration risks.

Related skills

Validation

→Data Parity

Prove two datasets match after a migration, refactor, or rewrite.

Lineage

→Lineage Diff

Show how data flow changed, not just how SQL text changed.

dbt

→dbt Analyze

Understand downstream impact before changing a model.

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