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The following list describes some of the important characteristics
of the MySQL Database Software. See section MySQL 4.0 in a Nutshell.
Written in C and C++.
Tested with a broad range of different compilers.
Works on many different platforms. See section Operating Systems Supported by MySQL.
Uses GNU Automake, Autoconf, and Libtool for portability.
APIs for C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl are available. See section MySQL APIs.
Fully multi-threaded using kernel threads. This means it can easily use multiple CPUs if they are available.
Provides transactional and non-transactional storage engines.
Uses very fast B-tree disk tables (MyISAM) with index compression.
Relatively easy to add another storage engine. This is useful if you want to add an SQL interface to an in-house database.
A very fast thread-based memory allocation system.
Very fast joins using an optimized one-sweep multi-join.
In-memory hash tables, which are used as temporary tables.
SQL functions are implemented using a highly optimized class library and should be as fast as possible. Usually there is no memory allocation at all after query initialization.
The MySQL code is tested with Purify
(a commercial memory leakage detector) as well as with Valgrind,
a GPL tool (http://developer.kde.org/~sewardj/).
The server is available as a separate program for use in a client/server networked environment. It is also available as a library that can be embedded (linked) into standalone applications. Such applications can be used in isolation or in environments where no network is available.
Many column types: signed/unsigned integers 1, 2, 3, 4, and 8 bytes
long, FLOAT, DOUBLE, CHAR, VARCHAR,
TEXT, BLOB, DATE, TIME, DATETIME,
TIMESTAMP, YEAR, SET, ENUM, and OpenGIS geometry
types.
See section Column Types.
Fixed-length and variable-length records.
Full operator and function support in the SELECT and WHERE
clauses of queries. For example:
mysql> SELECT CONCAT(first_name, ' ', last_name)
-> FROM tbl_name
-> WHERE income/dependents > 10000 AND age > 30;
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Full support for SQL GROUP BY and
ORDER BY clauses. Support
for group functions (COUNT(),
COUNT(DISTINCT ...),
AVG(), STD(),
SUM(), MAX(), MIN(), and GROUP_CONCAT()).
Support for LEFT OUTER JOIN and RIGHT OUTER JOIN with both standard
SQL and ODBC syntax.
Support for aliases on tables and columns as required by standard SQL.
DELETE, INSERT, REPLACE, and UPDATE return
the number of rows that were changed (affected). It is possible to return
the number of rows matched instead by setting a flag when connecting to the
server.
The MySQL-specific SHOW command can be used to retrieve
information about databases, tables, and indexes. The EXPLAIN command
can be used to determine how the optimizer resolves a query.
Function names do not clash with table or column names. For example,
ABS is a valid column name. The only restriction is that for a
function call, no spaces are allowed between the function name and the
`(' that follows it. See section Treatment of Reserved Words in MySQL.
You can mix tables from different databases in the same query (as of Version 3.22).
A privilege and password system that is very flexible and secure, and allows host-based verification. Passwords are secure because all password traffic is encrypted when you connect to a server.
Handles large databases. We use MySQL Server with databases that
contain 50 million records. We also know of users who
use MySQL Server with 60,000 tables and about 5,000,000,000 rows.
Up to 64 indexes per table are allowed (32 before MySQL 4.1.2). Each index may
consist of 1 to 16 columns or parts of columns. The maximum index width is
1000 bytes (500 before MySQL 4.1.2).
An index may use a prefix of a CHAR or VARCHAR column.
Clients may connect to the MySQL server using TCP/IP sockets
on any platform. On Windows systems in the NT family (NT, 2000,
or XP), clients may connect using named pipes. On Unix systems,
clients may connect using Unix domain socket files.
The Connector/ODBC interface provides MySQL support for client programs
that use ODBC (Open Database Connectivity) connections. For example,
you can use MS Access to connect to your MySQL server. Clients may
be run on Windows or Unix. Connector/ODBC source is available. All ODBC
2.5 functions are supported, as are many others.
See section MySQL ODBC Support.
The Connector/JDBC interface provides MySQL support for Java client
programs that use JDBC connections. Clients may be run on Windows or Unix.
Connector/JDBC source is available.
See section MySQL Java Connectivity (JDBC).
The server can provide error messages to clients in many languages. See section Setting the Error Message Language.
Full support for several different character sets, including
ISO-8859-1 (Latin1), german, big5, ujis, and more. For example,
the Scandinavian characters `â', `ä' and `ö' are
allowed in table and column names.
Unicode support is available as of MySQL 4.1.
All data is saved in the chosen character set. All comparisons for normal string columns are case-insensitive.
Sorting is done according to the chosen character set (the Swedish
way by default). It is possible to change this when the MySQL
server is started. To see an example of very advanced sorting, look
at the Czech sorting code. MySQL Server supports many different
character sets that can be specified at compile time and runtime.
The MySQL server has built-in support for SQL statements to check,
optimize, and repair tables. These statements are available from the
command line through the mysqlcheck client. MySQL also includes
myisamchk, a very fast command-line utility for performing these
operations on MyISAM tables.
See section Database Administration.
All MySQL programs can be invoked with the --help or -?
options to obtain online assistance.
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