PostgreSQL Zero-Downtime Migration and Future Read/Write Split via Pgcat

1. Goals

2. Architecture Overview

Before Migration

Applications → Pgcat → PostgreSQL 11 (source)

During Migration

Applications → Pgcat → PostgreSQL 11 (source)

pgcopydb performs:
1. Full copy into PostgreSQL 14 (target)
2. Continuous logical replication (changes from PG11 → PG14)

After Cutover

Applications → Pgcat → PostgreSQL 14 (target, primary)

3. Components

Pgcat

pgcopydb

Native Logical Replication

4. Migration Flow (High-Level)

Step 1 — Deploy Pgcat in Front of the Existing Database

Step 2 — Prepare the Target Database (PostgreSQL 14)

Step 3 — Run pgcopydb

Step 4 — Catch-Up and Pre-Cutover Freeze

Step 5 — Cutover via Pgcat

Step 6 — Post-Cutover Validation and Teardown

5. Future Read/Write Split

Read/Write Split Mode

6. Benefits of This Approach

7. Summary

Related Documentations