MySQL Storage Engines: Overview, Differences, and Interview Guidance

MySQL supports multiple storage engines. You can list them with the SHOW ENGINES command.

The current default engine (MySQL 8.x) is InnoDB, which is the only transactional engine. Earlier versions (≤5.5.5) used MyISAM as the default.

Use SELECT VERSION() to check the MySQL version, and SHOW VARIABLES LIKE '%storage_engine%' to see the default storage engine.

MySQL uses a pluggable architecture: each table can be assigned a specific engine, and engines are implemented as plugins.

Key differences between InnoDB and MyISAM:

Locking: InnoDB supports row‑level locking; MyISAM only provides table‑level locking.

Transactions: InnoDB offers full ACID transaction support; MyISAM does not support transactions.

Foreign keys: supported by InnoDB, not by MyISAM.

Crash recovery: InnoDB uses redo logs for safe recovery; MyISAM cannot guarantee recovery after a crash.

MVCC: available in InnoDB, absent in MyISAM.

Index implementation: InnoDB stores data in clustered B+Tree indexes; MyISAM stores data separately from its indexes.

Performance: InnoDB scales with CPU cores and concurrent workloads; MyISAM lacks concurrent write capability.

Caching: InnoDB uses a buffer pool for both data and index pages; MyISAM uses a key cache only for index pages.

In most production scenarios InnoDB is the recommended engine. MyISAM may be chosen for read‑intensive workloads where transaction support and crash recovery are not required.

For deeper details refer to the official MySQL documentation on InnoDB and other storage engines.