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2.6.1.7 MySQL for Windows Compared to Unix MySQL

MySQL for Windows has by now proven itself to be very stable. The Windows version of MySQL has the same features as the corresponding Unix version, with the following exceptions:

Windows 95 and threads
Windows 95 leaks about 200 bytes of main memory for each thread creation. Each connection in MySQL creates a new thread, so you shouldn't run mysqld for an extended time on Windows 95 if your server handles many connections! Other versions of Windows don't suffer from this bug.
Concurrent reads
MySQL depends on the pread() and pwrite() calls to be able to mix INSERT and SELECT. Currently we use mutexes to emulate pread()/pwrite(). We will, in the long run, replace the file level interface with a virtual interface so that we can use the readfile()/writefile() interface on NT/2000/XP to get more speed. The current implementation limits the number of open files MySQL can use to 1024, which means that you will not be able to run as many concurrent threads on NT/2000/XP as on Unix.
Blocking read
MySQL uses a blocking read for each connection, which has the following implications:
  • A connection will not be disconnected automatically after 8 hours, as happens with the Unix version of MySQL.
  • If a connection hangs, it's impossible to break it without killing MySQL.
  • mysqladmin kill will not work on a sleeping connection.
  • mysqladmin shutdown can't abort as long as there are sleeping connections.
We plan to fix this problem when our Windows developers have figured out a nice workaround.
DROP DATABASE
You can't drop a database that is in use by some thread.
Killing MySQL from the task manager
You can't kill MySQL from the task manager or with the shutdown utility in Windows 95. You must take it down with mysqladmin shutdown.
Case-insensitive names
Filenames are case-insensitive on Windows, so database and table names are also case-insensitive in MySQL for Windows. The only restriction is that database and table names must be specified using the same case throughout a given statement. See section 6.1.3 Case Sensitivity in Names.
The `\' directory character
Pathname components in Windows 95 are separated by the `\' character, which is also the escape character in MySQL. If you are using LOAD DATA INFILE or SELECT ... INTO OUTFILE, you must double the `\' character: 
mysql> LOAD DATA INFILE "C:\\tmp\\skr.txt" INTO TABLE skr;
mysql> SELECT * INTO OUTFILE 'C:\\tmp\\skr.txt' FROM skr;
Alternatively, use Unix style filenames with `/' characters: 
mysql> LOAD DATA INFILE "C:/tmp/skr.txt" INTO TABLE skr;
mysql> SELECT * INTO OUTFILE 'C:/tmp/skr.txt' FROM skr;
Problems with pipes.
Pipes doesn't work reliably in the Windows command-line prompt. If the pipe includes the character ^Z / CHAR(24), Windows will think it has encountered end-of-file and abort the program. This is mainly a problem when you try to apply a binary log as follows: 
mysqlbinlog binary-log-name | mysql --user=root
If you get a problem applying the log and suspect it's because of an ^Z / CHAR(24) character you can use the following workaround: 
mysqlbinlog binary-log-file --result-file=/tmp/bin.sql
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.
Can't open named pipe error
If you use a MySQL 3.22 version on NT with the newest mysql-clients you will get the following error: 
error 2017: can't open named pipe to host: . pipe...
This is because the release version of MySQL uses named pipes on NT by default. You can avoid this error by using the --host=localhost option to the new MySQL clients or create an option file `C:\my.cnf' that contains the following information: 
[client]
host = localhost
Starting from 3.23.50, named pipes are enabled only if mysqld-nt or mysqld-max-nt is started with --enable-named-pipe.
Access denied for user error
If you get the error Access denied for user: 'some-user@unknown' to database 'mysql' when accessing a MySQL server on the same machine, this means that MySQL can't resolve your host name properly. To fix this, you should create a file `\windows\hosts' with the following information: 
127.0.0.1       localhost
ALTER TABLE
While you are executing an ALTER TABLE statement, the table is locked from usage 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 threads. (In the future, we may find some way to work around this problem.)
DROP TABLE
DROP TABLE on a table that is in use by a MERGE table will not work on Windows because the MERGE handler does the table mapping hidden from the upper layer of MySQL. Because Windows doesn't allow you to drop files that are open, you first must flush all MERGE tables (with FLUSH TABLES) or drop the MERGE table before dropping the table. We will fix this at the same time we introduce VIEWs.
DATA DIRECTORY and INDEX DIRECTORY
The DATA DIRECTORY and INDEX DIRECTORY options for CREATE TABLE are ignored on Windows, because Windows doesn't support symbolic links.

Here are some open issues for anyone who might want to help us with the Windows release:

Other Windows-specific issues are described in the `README' file that comes with the Windows distribution of MySQL.

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