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Frequently Asked Questions
MYSQL
Which are the program specifications?
Platforms
MySQL works on many different platforms, including AIX, BSDi, FreeBSD, HP-UX, GNU/Linux, Mac OS X, NetBSD, Novell NetWare, OpenBSD, OS/2 Warp, QNX, SGI IRIX, Solaris, SunOS, SCO OpenServer, SCO UnixWare, Tru64, Windows 95, Windows 98, Windows ME, Windows NT, Windows 2000, Windows XP and more recent versions of Windows. A port of MySQL to OpenVMS is also available.
The latest production version
As of October 2006, MySQL offers production version 5.0.27 (Community Server) and 5.0.28 (Enterprise Server). It includes the following features:
A broad subset of ANSI SQL 99, as well as extensions
Cross-platform support
Stored procedures
Triggers
Cursors
Updatable Views
True VARCHAR support
INFORMATION_SCHEMA
Strict mode
X/Open XA distributed transaction processing (DTP) support; two phase commit as part of this, using Oracle's InnoDB engine
Independent storage engines (MyISAM for read speed, InnoDB for transactions and referential integrity, Archive for storing historical data in little space)
Transactions with the InnoDB, BDB and Cluster storage engines; savepoints with InnoDB
SSL support
Query caching
Sub-SELECTs (i.e. nested SELECTs)
Replication with one master per slave, many slaves per master, no automatic support for multiple masters per slave.
Full-text indexing and searching using MyISAM engine
Embedded database library
Partial Unicode support (UTF-8 sequences longer than 3 bytes are not supported; UCS-2 encoded strings are also limited to the BMP)
ACID compliance using the InnoDB, BDB and Cluster engines
Shared-nothing clustering through MySQL Cluster
Future releases
The MySQL 5.1 roadmap outlines support for: Partitioning; Online backup for all storage engines; Fail-safe replication; Column-level constraints; Event Scheduling; XML functions.
Foreign key support for all storage engines will likely be released with MySQL 5.2 (although it has been present since version 3.23.44 for InnoDB).
Distinguishing features
The following features are implemented by MySQL but not by some other RDBMSes:
- Multiple storage engines (MyISAM, Merge, InnoDB, BDB, Memory/heap, Cluster, Federated, Archive, CSV, Blackhole and Example in 5.x), letting you choose the one which is most effective for each table in the application.
- Commit grouping, gathering multiple transactions from multiple connections together to increase the number of commits per second.
Server compilation type
There are 3 types of MySQL Server Compilations:
- Standard: The MySQL-Standard binaries are recommended for most users, and include the InnoDB storage engine.
- Max: (not MaxDB, which is a cooperation with SAP) is mysqld-max Extended MySQL Server. The MySQL-Max binaries include additional features that may not have been as extensively tested or are not required for general usage.
- The MySQL-Debug binaries have been compiled with extra debug information, and are not intended for production use, because the included debugging code may cause reduced performance.
Beginning with MySQL 5.1, MySQL AB has stopped providing three different package variants. There will only be one MySQL server package, which includes a mysqld binary with all functionality and storage engines enabled. Instead of providing a separate debug package, a server binary with extended debugging information is also included in the standard package, named mysqld-debug mm.
Source code specifics
MySQL is written in C. The SQL parser uses yacc and home-brewed lexer. A document describing some of the internal structures of the code and the coding guidelines is available from the MySQL web site.
