c37016b0e5
tmp_memory_table_size is limiting the size of internal temporary memory tables. max_heap_table_size is there to limiting the size of explictely created memory tables. max_heap_table_size can be much larger than tmp_memory_table_size as the memory used by temporary tables is in the control of the user. This commit changes the usage of max_heap_table_size for internal buffers to min(max_heap_table_size, tmp_memory_table_size), like we do for internal temporary tables. This changes the in memory buffer allocations for: - GROUP_CONCAT() - Calculating the cost for scanning memory tables (the original code was wrong here as it used the wrong size for memory tables). - ANALYZE TABLE buffer sizes for calculating distinct column values Other things: - Add THD::ram_limitation() to provide consistent memory limitations in all code that used variables.tmp_memory_table_size as buffers. If tmp_memory_table_size == 0, then 8192 is used. This replaces Item_sum::ram_limitation which used 1024 as min buffer, which is way to little for any practical case. - Added security guard in heap_prepare_hp_create_info to ensure that max_table_size is calculated same way as in MariaDB server. - Fixed initial memory allocations for Item_func_group::concat which allocated 'max allowed memory' at start. Now it allocates only 1/16 of that memory at start.
MariaDB Server
MariaDB Server is one of the most widely deployed open source relational databases. It is built by a global community of contributors together with the MariaDB Foundation and MariaDB plc, and it powers workloads from small applications to large-scale production systems.
MariaDB began as a fork of MySQL, led by the original MySQL developers, and it maintains a high degree of MySQL compatibility. It has since grown into a database with its own capabilities, including native vector search, multiple pluggable storage engines, synchronous clustering, and analytical features, while remaining a straightforward migration target for existing MySQL deployments.
Key features
- Native vector search. A built-in VECTOR data type with approximate nearest-neighbour indexing (HNSW), available since MariaDB 11.8 with no extension required.
- Pluggable storage engines. InnoDB (default for transactional workloads), Aria, MyRocks, ColumnStore for analytics, Spider for sharding, and S3 for archival, among others.
- Replication and clustering. Asynchronous, semi-synchronous, and parallel replication with global transaction IDs, plus Galera synchronous multi-primary clustering.
- Advanced SQL. Common table expressions and recursive CTEs, window functions, system-versioned (temporal) tables, sequences, and a broad set of JSON functions.
- MySQL and Oracle compatibility. Wire-protocol and syntax compatibility with MySQL, plus an Oracle SQL mode supporting PL/SQL-style stored routines.
- Spatial and full-text search. GIS data types and functions, and built-in full-text indexing.
- Security. Role-based access control, pluggable authentication (ed25519, PAM, GSSAPI, and more), data-at-rest encryption, and TLS for connections.
Documentation
- Project home, community, and getting involved
- Reference manual and release notes
- MariaDB compared to MySQL
Releases
MariaDB Server follows a yearly long-term support (LTS) model alongside quarterly rolling releases. Binary LTS releases are maintained for three years and are recommended for production; rolling releases deliver new features sooner with a shorter support window.
For the current version and full history, see Releases and the MariaDB release calendar.
Installing
Packages and installation instructions for all supported platforms are available at https://mariadb.org/download/.
Building from source
To build MariaDB from source and run the test suite, follow the developer guide
It covers building the code correctly, running the MariaDB testing framework, and choosing the right branch to target for contributions.
Contributing
Contributions are welcome, from code and documentation to bug reports and reviews. See CONTRIBUTING.md to get started, and CODING_STANDARDS.md for code style. Contributors and community members are recognised in CREDITS.
Getting help
- Zulip chat
- Maria Discuss mailing list
- Bug reports
- Security vulnerabilities: see SECURITY.md
Licensing
MariaDB Server is licensed under version 2 of the GNU General Public License (GPLv2), without the "any later version" clause. This is inherited from MySQL. License information is in the COPYING file, and third-party license information is in the THIRDPARTY file.
About MariaDB Foundation
MariaDB is brought to you by the MariaDB Foundation and MariaDB plc. The MariaDB Foundation is the custodian of the MariaDB Server codebase, ensuring it stays open and that anyone can contribute. See CREDITS for details on the Foundation and the people developing MariaDB.
MySQL, the base of MariaDB, is a product and trademark of Oracle Corporation, Inc.