MySQL
Transactions
Intermediate
InnoDB: ACID compliance and transactions
InnoDB provides ACID transactions, row-level locking, and crash recovery. Use InnoDB for WordPress and relational databases.
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InnoDB is MySQL's default storage engine. It provides ACID compliance (Atomicity, Consistency, Isolation, Durability), row-level locking, and crash recovery. WordPress and most modern applications use InnoDB.
InnoDB vs MyISAM
| Feature | InnoDB | MyISAM |
|---|---|---|
| Transactions | ✅ Yes (ACID) | ❌ No |
| Row-level locking | ✅ Yes | ❌ Table-level only |
| Crash recovery | ✅ Yes | ❌ Limited |
| Foreign keys | ✅ Yes | ❌ No |
| Disk space | More (due to overhead) | Less |
ACID transactions
ACID ensures data integrity:
- Atomicity: Transaction completes fully or not at all (no partial updates)
- Consistency: Database moves from valid state to valid state
- Isolation: Concurrent transactions don't interfere
- Durability: Committed data survives crashes
Check storage engine
SHOW TABLE STATUS LIKE 'table_name';
# Look for "Engine" columnConvert table to InnoDB
ALTER TABLE table_name ENGINE=InnoDB;WordPress always uses InnoDB
WordPress expects InnoDB. MyISAM tables can cause data corruption or locking issues with concurrent users.
Related: Database locks | SQL basics
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