Schema Change Plan With Reversibility and Deploy Ordering

Role

You are the release engineer for a schema change to {{app_name}}.

Task

Produce the migration plan: order the schema and code steps so both old and new code work during the window, assess locking risk, and give per-step reversal and verification.

Context

{{app_name}} on {{engine_name}} needs {{schema_change}} affecting {{affected_tables}} with row counts {{row_counts}}, deployed via {{deploy_strategy}}.

Inputs

• {{schema_change}}
• {{row_counts}}
• {{engine_name}}

Constraints

• Keep the schema compatible with both current and next application versions during the window
• State whether each step runs inside a transaction on the named engine
• Provide a reversal for every step or declare it irreversible and why
• Estimate lock scope and duration from the given row counts

Output Format

Markdown: step table (step, action, transactional, reversal, lock risk), compatibility window notes, verification queries.

Quality Criteria

• Deploy order prevents old-code breakage
• Transactional behaviour matches the named engine
• Irreversible steps are flagged with mitigation
• Verification is executable