Best Free and Open Source Alternatives to Microsoft SQL Server

Microsoft’s relationship with open source software has changed considerably over the years. Once openly hostile to Linux and free software, the company now contributes to open source projects and supports Linux across parts of its ecosystem. Nevertheless, much of Microsoft’s software portfolio remains proprietary.

This series looks at the best free and open source alternatives to products and services offered by Microsoft.

Microsoft SQL Server is a relational database management system designed for storing, processing and securing structured data. It supports transactional workloads, stored procedures, triggers, views, indexing, replication, backup and recovery, and uses Microsoft’s Transact-SQL (T-SQL) dialect.

SQL Server is available for Linux, but it remains proprietary software. There is no direct drop-in open source replacement, particularly where an application makes extensive use of T-SQL or SQL Server-specific services. But there are some excellent free and open source relational database systems.

1. PostgreSQL

PostgreSQL is a powerful object-relational database management system with a long history of development and an excellent reputation for reliability, data integrity and standards compliance.

It offers ACID transactions, sophisticated indexing, views, triggers, stored procedures, window functions, common table expressions, partitioning, replication and point-in-time recovery. PostgreSQL is also highly extensible, with support for additional data types, procedural languages and extensions.

For organisations migrating substantial applications away from SQL Server, PostgreSQL is an especially compelling option. Its rich SQL implementation and strong transactional capabilities make it suitable for everything from conventional business applications to large, demanding database installations.

2. Firebird

Firebird is a mature relational database with a relatively small footprint but an extensive feature set.

It supports ACID transactions, stored procedures, triggers, views, referential integrity, multi-version concurrency control and sophisticated transaction isolation. Firebird can operate as a conventional database server or as an embedded database.

The software is particularly attractive where administrators want a capable SQL server without the complexity and resource requirements associated with some larger database platforms. Its strong stored procedure and trigger support also makes it worth considering for applications moving away from SQL Server.

3. MariaDB

MariaDB is a widely deployed relational database server that originated as a fork of MySQL.

It offers transactions, foreign keys, views, triggers, stored procedures, replication, clustering and a choice of storage engines. There is a large ecosystem of drivers, administration tools and application frameworks with MariaDB support.

MariaDB is not compatible with T-SQL, so migrating a SQL Server application may require substantial changes to database code. But for applications that primarily require a reliable multi-user relational database, it is a mature and well-supported choice.

4. MySQL

MySQL is a popular multi-user relational database management system. Its Community Edition is free and open source software licensed under the GNU General Public License.

The InnoDB storage engine provides ACID transactions, row-level locking, crash recovery and foreign key support. MySQL also offers views, triggers, stored procedures, replication, partitioning and a very large selection of client libraries and third-party tools.

Its enormous application ecosystem makes MySQL particularly appealing for web services and general-purpose application development. As with MariaDB, applications making significant use of SQL Server-specific SQL will need adapting.

5. CUBRID

CUBRID is a relational database management system with features aimed at transactional and enterprise workloads.

It provides ACID transactions, referential integrity, indexes, joins, nested queries, triggers, stored procedures, replication, high availability, connection pooling and online and incremental backups.

CUBRID has a much smaller ecosystem than PostgreSQL, MariaDB or MySQL, but it remains an interesting option for users looking for a traditional client-server relational database with built-in high-availability and scaling features.

For more choices, see our roundup of the best free and open source relational databases.

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Alternatives to Microsoft's Products and Services
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