MySQL for Windows has proven itself to be very stable. The Windows version of MySQL has the same features as the corresponding Unix version, with the following exceptions:
Limited number of ports
Windows systems have about 4,000 ports available for client connections, and after a connection on a port closes, it takes two to four minutes before the port can be reused. In situations where clients connect to and disconnect from the server at a high rate, it is possible for all available ports to be used up before closed ports become available again. If this happens, the MySQL server appears to be unresponsive even though it is running. Note that ports may be used by other applications running on the machine as well, in which case the number of ports available to MySQL is lower.
For more information about this problem, see http://support.microsoft.com/default.aspx?scid=kb;en-us;196271.
MySQL depends on the
pwrite() system calls to be able to mix
SELECT. Currently, we use
mutexes to emulate
pwrite(). We intend to replace the file
level interface with a virtual interface in the future so
that we can use the
interface to get more speed. The current implementation
limits the number of open files that MySQL 5.1
can use to 2,048, which means that you cannot run as many
concurrent threads on Windows as on Unix.
MySQL uses a blocking read for each connection. That has the following implications if named-pipe connections are enabled:
A connection is not disconnected automatically after eight hours, as happens with the Unix version of MySQL.
If a connection hangs, it is not possible to break it without killing MySQL.
mysqladmin kill does not work on a sleeping connection.
mysqladmin shutdown cannot abort as long as there are sleeping connections.
We plan to fix this problem in the future.
While you are executing an
TABLE statement, the table is locked from being
used by other threads. This has to do with the fact that on
Windows, you can't delete a file that is in use by another
thread. In the future, we may find some way to work around
DROP TABLE on a table that is
in use by a
MERGE table does not work on
Windows because the
MERGE handler does
the table mapping hidden from the upper layer of MySQL.
Because Windows does not allow dropping files that are open,
you first must flush all
TABLES) or drop the
before dropping the table.
DATA DIRECTORY and
DATA DIRECTORY and
DIRECTORY options for
TABLE are ignored on Windows, because Windows
doesn't support symbolic links. These options also are
ignored on systems that have a nonfunctional
You cannot drop a database that is in use by some thread.
File names are not case sensitive on Windows, so MySQL database and table names are also not case sensitive on Windows. The only restriction is that database and table names must be specified using the same case throughout a given statement. See Section 8.2.2, “Identifier Case Sensitivity”.
Directory and file names
On Windows, MySQL Server supports only directory and file names that are compatible with the current ANSI code pages. For example, the following Japanese directory name will not work in the Western locale (code page 1252):
The same limitation applies to directory and file names
referred to in SQL statements, such as the data file path
\” path name separator
Path name components in Windows are separated by the
\” character, which is also
the escape character in MySQL. If you are using
SELECT ... INTO
OUTFILE, use Unix-style file names with
LOAD DATA INFILE 'C:/tmp/skr.txt' INTO TABLE skr;mysql>
SELECT * INTO OUTFILE 'C:/tmp/skr.txt' FROM skr;
Alternatively, you must double the
LOAD DATA INFILE 'C:\\tmp\\skr.txt' INTO TABLE skr;mysql>
SELECT * INTO OUTFILE 'C:\\tmp\\skr.txt' FROM skr;
Problems with pipes
Pipes do not work reliably from the Windows command-line
prompt. If the pipe includes the character
thinks that it has encountered end-of-file and aborts the
This is mainly a problem when you try to apply a binary log as follows:
binary_log_file| mysql --user=root
If you have a problem applying the log and suspect that it
is because of a
CHAR(24) character, you can use the
mysql --user=root --execute "source /tmp/bin.sql"
The latter command also can be used to reliably read in any SQL file that may contain binary data.
Access denied for
If MySQL cannot resolve your host name properly, you may get the following error when you attempt to run a MySQL client program to connect to a server running on the same machine:
Access denied for user '
some_user'@'unknown' to database 'mysql'
To fix this problem, you should create a file named
\windows\hosts containing the following
Here are some open issues for anyone who might want to help us improve MySQL on Windows:
Add macros to use the faster thread-safe increment/decrement methods provided by Windows.