zero-downtime-migration

SKILL.md

Database migration patterns that ensure continuous service availability during schema changes.

| Tool choice | pgroll for automation | Handles dual-writes via triggers automatically | | Column Rename | Add new + copy + drop old | Direct RENAME blocks reads | | Constraint Timing | Add NOT VALID first, VALIDATE separately | NOT VALID is non-blocking | | Rollback Window | Keep old schema 24-72 hours | Allows safe rollback if issues |

| Backfill Batch Size | 1000-10000 rows per batch | Prevents lock escalation | | Index Strategy | CONCURRENTLY always | Standard CREATE INDEX locks table | | Verification | Check pgstatstatements | Ensure no queries use old columns |

Safe database schema changes without downtime using expand-contract pattern and online schema changes. Use when deploying schema changes to production without service interruption. Source: yonatangross/skillforge-claude-plugin.

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