Migrating to MySQL: Step-by-Step Checklist and Common PitfallsMigrating a database to MySQL can improve performance, reduce costs, and simplify operations — but only if planned and executed carefully. This step-by-step guide walks you through preparation, migration, validation, and post-migration tasks, plus common pitfalls and how to avoid them.
Why migrate to MySQL?
MySQL is a mature, widely supported relational database with a large ecosystem, strong community, and multiple distribution options (Oracle MySQL, MariaDB, Percona Server). Reasons teams choose MySQL include lower licensing cost than some enterprise DBs, rich tooling, reliable replication, and cloud-managed offerings (e.g., Amazon RDS, Google Cloud SQL, Azure Database for MySQL).
Pre-migration planning
1) Define goals and success criteria
- Identify why you’re migrating (performance, cost, vendor lock-in, features).
- Define measurable success criteria: latency, throughput, failover RTO/RPO, budget, and timeline.
- Determine rollback criteria if migration fails.
2) Inventory current system
- Catalog schemas, tables, row counts, indexes, stored procedures, triggers, views, and user-defined functions.
- List application dependencies, ORM versions, connection pools, and middleware.
- Note data size (raw and compressed), growth rates, and peak traffic patterns.
3) Assess compatibility
- Compare source database features with MySQL equivalents (data types, functions, stored procedures, triggers, views, constraints).
- Identify SQL dialect differences (e.g., LIMIT vs TOP, window function behavior, procedural language differences).
- Check for use of non-standard SQL or vendor-specific extensions.
4) Choose MySQL distribution and edition
- Decide between Oracle MySQL, MariaDB, Percona Server, or a cloud-managed MySQL service.
- Evaluate features needed: GIS support, JSON performance, InnoDB enhancements, audit, encryption, backup tooling.
- Plan version target (ideally latest stable supported by your platform) and upgrade path.
5) Design target schema and environment
- Map source schema to MySQL types; adjust where necessary (e.g., NUMERIC/DECIMAL precision, ENUM usage, BOOLEAN mapping).
- Choose storage engine (InnoDB recommended for ACID compliance and row-level locking).
- Plan indexing strategy and consider schema changes to improve performance (normalization/denormalization decisions).
- Design capacity: CPU, RAM, disk IOPS, storage format (SSD), and backup storage.
6) Plan migration approach and tools
- Choose migration type: in-place convert, one-time bulk export/import, or continuous replication with cutover.
- Tools: mysqldump, mysqlpump, Percona XtraBackup (for physical copies), pt-online-schema-change, gh-ost, Tungsten Replicator, Debezium + Kafka for CDC, AWS DMS, or vendor-specific migration tools.
- Decide on downtime window (if any) and whether zero-downtime migration is required.
Migration staging and testing
7) Build staging environment
- Provision a staging cluster that mirrors production topology (replication, read replicas, HA).
- Seed with representative data (full copy or sampled subset) and synthetic traffic to simulate load.
8) Convert schema and code
- Apply schema changes in staging, run migrations, and update stored procedures and triggers to MySQL syntax.
- Update application queries where SQL dialect differs. Pay special attention to:
- Date/time functions
- String functions and concatenation
- LIMIT/OFFSET, GROUP BY behavior, and handling of NULLs
- Review ORMs: some ORMs generate vendor-specific SQL; update configuration or queries as needed.
9) Import data (dry runs)
- Perform full data imports in staging using chosen tools. For large datasets, prefer physical backups or streaming replication methods to speed migration.
- Validate row counts, checksums (e.g., pt-table-checksum), and sample rows to ensure data fidelity.
- Measure import time and estimate production window.
10) Performance tuning in staging
- Tune MySQL configuration (innodb_buffer_pool_size, innodb_log_file_size, query_cache—deprecated, thread_pool, tmp_table_size, max_connections).
- Rebuild or add indexes where necessary.
- Run query profiling, slow query log analysis, and EXPLAIN plans to find regressions; add or adjust indexes and queries.
- Test backup and restore procedures.
Cutover strategy and execution
11) Select cutover method
- Full downtime: stop writes on source, take final export, import into MySQL, switch application.
- Blue/Green or parallel run: run both systems in parallel, route a subset of traffic to MySQL, compare results, then flip.
- Continuous replication (recommended for minimal downtime): set up real-time replication from source to MySQL with CDC, wait until lag is minimal, then cut over writes.
12) Prepare rollback and contingency plans
- Ensure backups are recent and tested.
- Confirm DNS or load balancer rollback procedures, and have clear steps to route traffic back to source.
- Ensure monitoring and alerting are active for both systems.
13) Execute migration
- Communicate maintenance windows to stakeholders.
- Disable non-critical background jobs and cron writes.
- Apply final data sync (for CDC/replication approaches) and stop writes to source at cutover time if required.
- Redirect application connections to MySQL. Monitor errors and latency closely.
Post-migration validation and hardening
14) Verify data integrity and application behavior
- Run automated test suites and smoke tests.
- Use checksums and row-count comparisons for critical tables.
- Validate reports and downstream consumers.
15) Monitor and optimize
- Monitor key metrics: query latency, error rate, replica lag, InnoDB metrics, buffer pool hit ratio, disk I/O, and CPU.
- Observe slow queries and tune indexes and queries.
- Adjust MySQL configuration based on real workload.
16) Security and maintenance
- Enforce least-privilege access, rotate credentials, and configure TLS for client connections.
- Enable audit logging if required and configure backups (logical and physical, point-in-time recovery with binary logs).
- Set up automated backups and periodic recovery tests.
17) Decommission and documentation
- After a stable period, decommission old databases safely.
- Document architecture, runbooks, schema changes, and lessons learned.
- Review cost, licensing, and operational metrics versus goals.
Common pitfalls and how to avoid them
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Pitfall: Underestimating compatibility differences
- Avoidance: Perform thorough SQL and feature compatibility analysis; convert and test stored procedures and triggers early.
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Pitfall: Insufficient capacity planning
- Avoidance: Test with production-like data volumes; size buffer pool and I/O for peak loads; use performance testing.
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Pitfall: Long migration windows for large datasets
- Avoidance: Use physical backups, streaming replication, or CDC tools to minimize downtime.
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Pitfall: Missing edge-case data conversions (character sets, timezones, NULL vs empty string)
- Avoidance: Validate character set and collation settings; test timezone handling; run comprehensive data validation.
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Pitfall: Neglecting transactional consistency during cutover
- Avoidance: Use replication/CDC with transaction ordering; stop application writes or quiesce systems during final sync.
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Pitfall: Hidden application dependencies (ORMs, middleware)
- Avoidance: Audit codebase for SQL generation, run integration tests, and include application teams in testing.
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Pitfall: Poor index strategy after migration
- Avoidance: Re-evaluate indexes under MySQL’s optimizer; use EXPLAIN and slow query logs to guide changes.
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Pitfall: Inadequate backup and recovery planning
- Avoidance: Implement redundant backup strategies and test restores regularly.
Quick checklist (one-page)
- Define goals, success metrics, rollback criteria
- Inventory schemas, objects, apps, and data size
- Choose MySQL distribution/version and storage engine
- Build staging and perform schema/code conversion
- Run dry-run imports and performance tests
- Choose cutover method (downtime vs CDC)
- Prepare backups, rollback plans, and communications
- Execute migration, run smoke tests
- Monitor, tune, and secure production
- Decommission old system and document
Final notes
Migrating to MySQL is a technical and organizational effort. Treat it as a project: involve DBAs, developers, QA, and operations early; iterate on staging until you have confidence; and prioritize data integrity and rollback safety over speed. With careful planning and testing you can minimize risk and gain the benefits MySQL offers.
Good luck with your migration.
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