When working with MySQL databases, the storage engine is a crucial component that determines how data is stored, indexed, and retrieved. The default storage engine in modern MySQL versions (5.5+) is InnoDB, but you might encounter older databases using MyISAM or other engines.

The most comprehensive way to check storage engines is to query the INFORMATION_SCHEMA:

SELECT TABLE_NAME, ENGINE 
FROM INFORMATION_SCHEMA.TABLES 
WHERE TABLE_SCHEMA = 'your_database_name';

For a specific table, you can use:

SHOW TABLE STATUS LIKE 'your_table_name';

This returns detailed information including the storage engine in the 'Engine' column.

When creating new tables, you can explicitly specify the storage engine:

CREATE TABLE example_table (
    id INT AUTO_INCREMENT PRIMARY KEY,
    data VARCHAR(255)
) ENGINE=InnoDB;

To convert an existing table to a different engine:

ALTER TABLE your_table_name ENGINE = InnoDB;

Note: This operation locks the table during conversion and may take time for large tables.

To see the default storage engine for your MySQL server:

SHOW VARIABLES LIKE 'default_storage_engine';

• InnoDB supports transactions, row-level locking, and foreign keys
• MyISAM offers full-text search but lacks transaction support
• Storage engine can significantly impact performance

Here's a complete example showing how to check and modify storage engines:

-- Check current default engine
SHOW VARIABLES LIKE 'default_storage_engine';

-- Create database (doesn't specify engine)
CREATE DATABASE test_db;

-- Create tables with different engines
CREATE TABLE test_db.table1 (id INT) ENGINE=InnoDB;
CREATE TABLE test_db.table2 (id INT) ENGINE=MyISAM;

-- Check engines for all tables in database
SELECT TABLE_NAME, ENGINE 
FROM INFORMATION_SCHEMA.TABLES 
WHERE TABLE_SCHEMA = 'test_db';

-- Change engine for one table
ALTER TABLE test_db.table2 ENGINE = InnoDB;

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When working with MySQL, the storage engine determines how your database handles SQL operations and stores data. The two most common engines are:

- MyISAM: Older engine with table-level locking (faster reads)
- InnoDB: Modern default with row-level locking (better for transactions)

To see your server's default storage engine:

SHOW VARIABLES LIKE 'default_storage_engine';

This returns output like:

+------------------------+--------+
| Variable_name          | Value  |
+------------------------+--------+
| default_storage_engine | InnoDB |
+------------------------+--------+

For any existing table, check its storage engine with:

SHOW TABLE STATUS LIKE 'table_name';

Or more concisely:

SELECT ENGINE 
FROM information_schema.TABLES 
WHERE TABLE_SCHEMA = 'your_db_name' 
AND TABLE_NAME = 'your_table_name';

Even though InnoDB has been MySQL's default since 5.5.5, several factors could result in MyISAM tables:

1. Legacy databases migrated from older MySQL versions
2. Explicit ENGINE=MyISAM in CREATE TABLE statements
3. Using FULLTEXT indexes (pre-MySQL 5.6)
4. Specialized use cases where MyISAM performs better

To convert an existing table to InnoDB:

ALTER TABLE table_name ENGINE=InnoDB;

For bulk conversion of all tables in a database:

SELECT CONCAT('ALTER TABLE ', TABLE_NAME, ' ENGINE=InnoDB;') 
FROM INFORMATION_SCHEMA.TABLES 
WHERE TABLE_SCHEMA = 'your_database'
AND ENGINE = 'MyISAM';

When creating new databases, explicitly specify the engine:

CREATE DATABASE new_db 
DEFAULT CHARACTER SET utf8mb4 
DEFAULT COLLATE utf8mb4_unicode_ci;

USE new_db;

CREATE TABLE important_data (
    id INT AUTO_INCREMENT PRIMARY KEY,
    content TEXT
) ENGINE=InnoDB;