Table of Contents
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MySQL is a mature client-server relational database. Typical deployments use InnoDB for ACID transactions, row-level locking, crash recovery, foreign keys, and clustered primary keys. It is not limited to legacy systems: predictable SQL, broad driver and ORM support, and abundant operational experience remain valuable for SaaS, commerce, and content workloads.
The core model is schema, constraints, and transactions
Encoding business invariants with NOT NULL, UNIQUE, foreign keys, and transactions is safer than expecting every handler to behave perfectly. Indexes are not free acceleration: secondary indexes consume space and amplify writes, while compound-index usefulness depends on column order and query shape. Use EXPLAIN ANALYZE against production-like data before choosing indexes.
InnoDB defaults to REPEATABLE READ; applications must still retry deadlocks and avoid long transactions. Bound connection pools as well. Unbounded serverless functions can exhaust database connections long before they provide unlimited throughput.
Replication does not guarantee zero data loss
MySQL replication is asynchronous by default. Replicas can scale reads, but lag breaks read-after-write assumptions. GTIDs simplify topology changes and failover; they do not choose promotion policy, drain connections, restore backups, or define RPO and RTO. Practice restores. A replica is not a backup because accidental deletes replicate too.
When to choose it
MySQL is a low-risk default when the team knows it, the workload is OLTP, relationships are clear, and hosting and tooling are mature. Choose PostgreSQL directly for a PostgreSQL-specific extension and type ecosystem. A changing document shape alone does not require MongoDB; inspect transaction and query boundaries first. Local analytics over Parquet or CSV belongs to DuckDB, not a production MySQL instance.
AI can draft migrations and queries, but it cannot own locking, online DDL, lag, or rollback. Popularity supplies many examples and many obsolete configurations; validate advice against the manual for the deployed version and a measured migration plan.
References
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