SQLite vs. MySQL: What are the differences between MySQL and SQLite?

If you're a developer or database administrator, you've almost certainly run into MySQL, and you may have worked with it. Another popular database technology is SQLite. Both are relational database management systems (RDBMS) widely used in web development, mobile applications, and other software projects. While both are SQL-based technologies for storing data, there are many differences between them, and each has its strengths and weaknesses.

In this article, we'll compare SQLite and MySQL in terms of their ideal use cases, features, performance, and other factors to help you decide which one is right for your project.

Architecture and Design

Like most popular RDBMSes, MySQL is a client-server database system. This means that it requires a server process to be running to handle client requests. This server process manages the database files and handles all the queries and data manipulation operations. The application that needs to interact with the database connects to the server process over a network connection, and the server handles all the database operations.

This design allows hosting a database server on a completely separate (and potentially isolated) machine from applications that use it, which can be beneficial for security and performance reasons. However, it also introduces additional complexity and overhead, as you need to manage the server process and ensure that it's running and accessible to clients. Setting up a MySQL server can be a complex process, especially if you're not familiar with server administration tasks.

SQLite, on the other hand, is a serverless database system. Instead of a separate server to handle client requests, the SQLite library is linked directly to the application that needs to interact with the database, and the application communicates directly with the library to read and write data right from a database file on disk. This design makes it easy to use SQLite, as you don't need to set up a separate server.

SQLite also stores the entire database in a single file, making it portable and easy to share between different systems. You can back it up simply by copying the file without a complex backup procedure. MySQL stores data in multiple files and directories, making backup and migration more difficult.

Data Types

MySQL and SQLite support several data types; however, the types work is quite different between the two.

MySQL has a rich set of data types, including integer, float, double, decimal, date, time, datetime, char, varchar, text, blob, and many others. Each data type has specific storage requirements and constraints, and you can choose the appropriate type based on the data you need to store. In MySQL, if you try to store a value that isn't compatible with the data type of a column, an error will likely occur (depending on the SQL mode).

SQLite is quite different, using 'flexible types' that allow you to store any type of data in any column, regardless of the declared type. SQLite has only these data types:

• integer: whole numbers
• real: floating-point numbers
• text: strings
• blob: binary data

These types are flexible and can store any kind of data. SQLite uses dynamic typing, which means that you can store an integer in a column that is declared as a text type, and SQLite will store the data without complaint. These aren't strict types in the way they are in MySQL but are more like suggestions — called 'type affinities' — for how to store the data.

The flexibility of SQLite's data types can be both a strength and a weakness. It makes it easy to store data without worrying about type conversions or errors, but it can also lead to data integrity issues if you're not careful. MySQL's strict data types can help prevent data corruption and ensure that the data is stored correctly.

Note that, despite the lack of dedicated time and date formats, SQLite does have date and time functions that can be used to store and manipulate date and time data as long as such data is stored in a format that SQLite can interpret as a date or time.

Concurrency and Transactions

Concurrency is the ability of a database system to handle multiple clients accessing and modifying data at the same time. Both MySQL and SQLite support concurrent access to the database, but they do so in different ways. MySQL uses a multi-threaded architecture to handle multiple client connections, with each connection running in its own thread. MySQL also employs locking mechanisms to prevent conflicts between clients that are trying to modify the same data, including row-level locking to ensure that only one client can modify a row at a time.

SQLite is not optimized for multiple concurrent users, allowing only one write operation at a time. However, multiple simultaneous read operations are supported. SQLite uses a simpler locking mechanism, locking the entire database file when a write operation is in progress. As a result, SQLite is not suitable for high-traffic websites or write-heavy applications that require high levels of concurrency.

Performance and Scalability

MySQL is designed to handle large-scale applications with high traffic and complex data requirements. It can handle thousands of concurrent connections and millions of rows of data, making it suitable for enterprise-level applications and websites. MySQL is highly scalable, with support for clustering and replication to distribute the load across multiple servers and ensure high availability. MySQL can scale to handle databases that are terabytes in size and support millions of transactions per second by using indexing, optimization, and support for different storage engines. Additionally, MySQL can scale horizontally with sharding, partitioning, and clustering across multiple servers.

Conversely, SQLite emphasizes simplicity and ease of use over performance and scalability. SQLite is designed for small-to-medium-sized applications that don't require high levels of concurrency or writing large amounts of data. SQLite is not suitable for high-traffic, write-heavy websites or applications that require high levels of concurrency, as it can become slow and unresponsive under heavy writing loads. SQLite is very fast for read-intensive applications and can support thousands of read operations per second. Theoretically, SQLite can handle databases up to 281 terabytes, but in practice, databases over several gigabytes may be slow unless you're almost entirely just reading from them.

Despite these limitations, SQLite is more than capable of handling embedded applications, mobile apps, and small to medium-sized web applications (particularly where it's unlikely many users will be writing often to the database at the same time.)

Security

The security of a database is incredibly important because it may contain sensitive or confidential information. MySQL has a number of security features to help protect your data, including user authentication, access control, encryption, and auditing. MySQL supports user accounts with different privileges, allowing you to control who can access the database and what operations they can perform. MySQL also supports SSL/TLS encryption for secure connections between clients and the server, as well as data-at-rest encryption to protect data stored on disk. Securely configuring a MySQL server can be complicated and takes some work, but you can make a system that is highly secure while being accessible to authorized users/clients.

SQLite is rather simple in its security model. There is no authentication, and there are no users or passwords. SQLite entirely relies on filesystem permissions and the physical security of the database file to protect data. If someone can access the file, they can read the data. This makes SQLite unsuitable for multi-user applications where you need to control access to the database. However, for single-user applications or embedded systems where the database file is protected, SQLite can be secure enough.

Use Cases and Applications

SQLite's simplicity and ease of use makes it ideal for the following types of applications:

• Mobile applications
• Embedded systems
• Small websites
• Prototyping and development
• Testing and QA
• Local storage for desktop applications

MySQL is better suited for the following types of applications:

• Large-scale websites and applications
• Enterprise-level applications
• E-commerce platforms
• Highly scalable content management systems
• Data warehousing and analytics

Licensing and Cost

SQLite is notably free and open-source software released into the public domain. This means you can use it for any purpose, commercial or non-commercial, without paying any licensing fees. SQLite is a popular choice for open-source projects and commercial applications alike because of its permissive licensing.

MySQL is free for most applications, but commercial licenses are available for proprietary projects that don't adhere to the requirements of the GNU General Public License (GPL). MySQL is owned by Oracle Corporation, which offers commercial support and services for MySQL, as well as enterprise features and add-ons that are not available in the open-source version.

An alternative fork of MySQL called MariaDB is also available. It is fully open-source and free to use. It is designed to be a community-driven drop-in replacement for MySQL that doesn't require a commercial license. MariaDB is fully compatible with MySQL, and they are often referred to interchangeably.

Conclusion

In summary, while MySQL and SQLite have many similarities, MySQL is more complex, more powerful, and more scalable. If you need a quick, easy-to-use data storage solution for a small web application or mobile app, SQLite is a great choice. If you're building a large-scale website or enterprise-level application that requires high levels of concurrency, security, and scalability, MySQL is the better option. Both databases have their strengths and weaknesses, and the best choice depends on your specific requirements and use case.

Here's a table summarizing the differences between SQLite vs. MySQL:

Feature	MySQL	SQLite
Architecture	Client-server	Serverless
Data Types	Many strict types	A few, flexible, dynamic types
Concurrency	High concurrency, row-level locking	Single-writer, file-level locking
Performance	Scalable for large, high-traffic apps	Best for small to medium apps, read-heavy
Security	User authentication, encryption	File system-based security
Use Cases	Enterprise apps, e-commerce, CMS	Mobile apps, embedded systems, prototyping
Cost	Free (GPL), commercial licenses available	Public domain, free to use