2 MySQL mailing lists and how to ask questions or report errors (bugs)

2.1 The MySQL mailing lists

Requests to be added to or dropped from the main MySQL mailing list should be sent to the electronic mail address mdomo@tcx.se. Sending a one-line message saying either subscribe mysql or unsubscribe mysql in the body of the message suffices. If your reply address is not valid, you may specify your address explicitly using subscribe mysql your-name@your.domain or unsubscribe mysql your-name@your.domain.

Please do not send mail about subscribing or unsubscribing to forwarded automatically to hundreds of other users.

Your local site may have many subscribers to mysql@tcx.se. If so, it may have a local mailing list, so that a single message from tcx.se is sent to the site and propagated to the local list. In such cases, please contact your system administrator to be added to or dropped from the local MySQL list.

Mail to mdomo@tcx.se is handled automatically by the Majordomo mailing list processor.

The following MySQL mailing lists exist:

mysql-announce

This is for announcement of new versions of MySQL and related programs. This is a low volume list that we think all MySQL users should be on.

mysql

The main list for general MySQL discussion. Please note that some things should go to the more-specialized lists. It you post to the wrong list, you may not get an answer!

mysql-digest

The mysql list in digest form. That means you get all individual messages, sent as one large mail message once a day.

mysql-Java

Discussion about MySQL and Java. Mostly about the JDBC drivers.

mysql-win32

All things concerning MySQL on Microsoft operating systems like Windows/NT.

myodbc

All things concerning connecting to MySQL with ODBC.

msql-mysql-modules

A list about the Perl support in MySQL.

msql-mysql-modules-digest

A digest version of the msql-mysql-modules list.

mysql-developer

A list for people who work on the MySQL code.

You subscribe or unsubscribe to all lists in the same way as described above. In your subscribe or unsubscribe request, just put the appropriate mailing list name rather than mysql.

2.2 Asking questions or reporting bugs

Before you ask a question on the mailing list, it is a good idea to check this manual. If you can't find an answer here, check with your local MySQL expert. If you still can't find an answer to your question, go ahead and read the next section about how to send mail to

2.3 How to report bugs or problems

Before posting a bug report or question, please start by searching the MySQL online manual http://www.mysql.com/Manual_chapter/manual_toc.html and the MySQL mailing list archives. We try to keep the manual up to date by updating it frequently with solutions to newly found problems! You can find the searchable mail archives at http://www.mysql.com/doc.html. You can also use http://www.mysql.com/search.html to search all the web pages (including the manual) at http://www.mysql.com/.

Writing a good bug report takes patience, but doing it right the first time saves time for us and for you. This section will help you write your report correctly so that you don't waste your time doing things that may not help us much or at all.

We encourage everyone to use the mysqlbug script to generate a bug report, or a report about any problem, if possible. mysqlbug can be found in the `scripts' directory in the source distribution, or, for a binary distribution, in the `bin' directory under your MySQL installation directory. If you are unable to use mysqlbug, you should still include all the necessary information listed in this section.

The mysqlbug script helps you generate a report by automatically finding a lot of the following information, but if something important is missing, please include it with your message! Please read this section carefully and make sure that all the information described here is included in your report.

Remember that it is possible to respond to a message containing too much information, but not to one containing too little. Often people omit facts because they think they know the cause of a problem and assume that some details don't matter. A good principle is: if you are in doubt about stating something, state it! It is a thousand times faster and less troublesome to write a couple of lines more in your report than to be forced to ask again and wait for the answer because you didn't include enough information the first time.

The most common errors are that people don't indicate the version number of the MySQL distribution they are using, or don't indicate what platform they have MySQL installed on (including the platform version number). This is very relevant information and in 99 cases out of 100 the bug report is useless without it! Very often we get questions like "Why doesn't this work for me?" and then we find that the feature requested wasn't implemented in that MySQL version, or that a bug described in a report has been fixed already in newer MySQL versions. Sometimes the error is platform dependent and it is next to impossible to fix anything without knowing the operating system and the version number of the platform.

Remember also to give information about your compiler, if it is related to the problem. Often people found bugs in compilers and think the problem is MySQL related. Most compilers are under development all the time and become better version by version too. To determine whether or not your problem depends on your compiler, we need to know what compiler is used. Note that every compiling problem should be regarded as a bug report and reported accordingly.

It is most helpful when a good description of the problem is included in the bug report. That is, a good example of all the things you did that led to the problem and the problem itself exactly described. The best bug reports are those that include a full example showing how to reproduce the bug or problem.

If a program produces an error message, it is very important to include the message in your report! If we try to search for something from the archives using programs, it is better that the error message reported exactly matches the one that the program produces. (Even the case sensitivity should be observed!) You should never try to remember what the error message was; instead, copy and paste the entire message into your report!

Please include the following information in your report:

• The version number of the MySQL distribution you are using (for example, MySQL 3.22.14b). You can find out which version you are running by executing mysqladmin version. mysqladmin can be found in the `bin' directory under your MySQL installation directory.
• The manufacturer and model of the machine you are working on.
• The operating system name and version. For most operating systems, you can get this by executing the Unix command uname -a.
• Sometimes the amount of memory (real and virtual) is relevant. If in doubt, include these values.
• If you are using a source distribution of MySQL, the name and version number of the compiler used is needed. If you have a binary distribution, the distribution name is needed.
• If the problem occurs during compilation, include the exact error message(s) and also a few lines of context around the offending code in the file where the error occurred.
• If any database table is related to the problem, include the output from mysqldump --no-data database table1 table2... This is very easy to do and is a powerful way to get information about any table in a database that will help us create a situation matching the one you have.
• For speed-related bugs or problems with SELECT statements, you should always include the output of EXPLAIN SELECT ..., and at least the number of rows that the SELECT statement produces.
• If a bug or problem bug occurs while running MySQL, try to provide an input script that will reproduce the bug. This script should include all the necessary source files, if any. The more closely the script can reproduce a situtation like yours, the better.
• If you think that MySQL produces a strange result from a query, include not only the result, but also your opinion of what the result should be and an account describing the basis for your opinion.
• When giving an example of the problem, it's better to use the variable names, table names, etc., that exist in the real situation than to come up with new names. The problem could be related to the name of a variable, table, etc.! These cases are rare, perhaps, but it is better to be safe than sorry. After all, it should be easier for you to use the same situation in your example that you really had and it is by all means better for us. In case you have some data you don't want to show to others, you can use ftp to transfer the data to ftp://www.mysql.com/pub/mysql/secret/. If the data are really top secret and you don't want to show them even to us, then go ahead and provide an example using other names, but please regard this as the last choice.
• Include all the options given to the relevant programs, if possible. For example, indicate the options that you use when you start the mysqld daemon and that you use to run any MySQL client programs. The options to programs like mysqld and mysql, and to the configure script are often keys to answers and very relevant! It is never a bad idea to include them anyway! If you use any modules, such as Perl or PHP, please include the version number(s) of those as well.
• If you can't produce a test case in a few rows, or if the test table is too big to be mailed to the mailing list (more than 10 rows), you should dump your tables using mysqldump and create a `README' file that describes your problem. Create a compressed archive of your files using tar and gzip or zip, and use ftp to transfer the archive to ftp://www.mysql.com/pub/mysql/secret/. Then send a short description of the problem to mysql@tcx.se.
• If your question is related to the privilege system, please include the output of mysqlaccess, the output of mysqladmin reload and all the error messages you get when trying to connect! When you test your privileges, you should first run mysqlaccess. After this, execute mysqladmin reload version, and last you should try to connect with the program that gives you trouble. mysqlaccess can be found in the `bin' directory under your MySQL installation directory.
• If you have a patch for a bug, this is good. But don't assume that the patch is all we need and that we will use it even if you don't provide some necessary information such as a test case showing the bug that your patch fixes. We might find problems with your patch or we might not understand it at all; if so, we can't use it. If we can't verify exactly what the patch is meant for, we won't use it. The test case will help us here. Show that the patch will handle all the situations that may occur. If we find a borderline case (even a rare one) where the patch won't work, the patch may be useless.
• Guesses about what the bug is, why it occurs, or what it depends on, are usually wrong. Even we can't guess such things without first using a debugger to determine the real cause of a bug.
• Indicate in your mail message that you have checked the reference manual and mail archive so others know that you have tried to solve your problem yourself.
• If you get a parse error, please check your syntax closely! If you can't find something wrong with it, it's extremely likely that your current version of MySQL doesn't support the query you are using. If you are using the current version and the manual at http://www.mysql.com/doc.html doesn't cover the query syntax you are using, this means that MySQL doesn't support your query. In this case, your only options are to implement the syntax yourself or email If the manual covers the syntax you are using, but you are using an older version of MySQL, you should check the MySQL change history for when the syntax was implemented. See section D MySQL change history. In this case you have the option of upgrading to a newer version of MySQL.
• If possible, download the newest MySQL version and check whether or not it solves your problem. All MySQL versions are throughly tested and should work without problems! We believe in making everything as backward compatible as possible and you should be able to switch MySQL versions in minutes! See section 4.3 Which MySQL version to use.

If you are a support customer, please crosspost the bug report to well as to the appropriate mailing list to see if someone else has experienced (and perhaps solved) the problem.

For information on reporting bugs in MyODBC, see section 15.2 How to report problems with MyODBC.

When answers are sent to you individually and not to the mailing list, it is considered good etiquette to summarize the answers and send the summary to the mailing list so that others may have the benefit of responses you received that helped you solve your problem!.

2.3.1 What to do if MySQL keeps crashing

Since it is very hard to know why something is crashing, first try to check whether or not things that work for others crash for you. Please try the following things:

• Have you tried the benchmarks? This should test MySQL rather well. You can also add code that simulates your application! The benchmarks can be found in the `bench' directory in the source distribution, or, for a binary distribution, in the `sql-bench' directory under your MySQL installation directory.
• Try fork_test.pl and fork2_test.pl.
• If you configure MySQL for debugging, it will be much easier to find out possible errors if something goes wrong. Reconfigure MySQL with the --with-debug option to configure and then recompile. See section 19.10 Debugging MySQL.
• Configuring MySQL for debugging causes a safe memory allocator to be included that can find some errors. It also provides a lot of output about what is happening.
• Use mysqld --log and try to determine from the information in the log whether or not some specific query kills the server. 95% of all bugs are related to some specific query!
• Have you applied the latest patches for your operating system?
• Use the --skip-locking option to mysqld. On some systems, the lockd lock manager does not work properly; the --skip-locking option tells mysqld not to use external locking. (This means that you cannot run 2 mysqld servers on the same data and you must be careful when using isamchk, but it may be instructive to try the option as a test.)
• Have you tried mysqladmin -u root processlist when mysqld appears to be running but not responding? Sometimes mysqld is not comatose even though you might think so. The problem may be that all connections are in use, or there may be some internal lock problem. mysqladmin processlist will usually be able to make a connection even in these cases, and can provide useful information about the current number of connections and their status.
• Run the command mysqladmin -i 5 status in a separate window to output statistics.
• Try the following:
  1. Start mysqld from gdb (or another debugger).
  2. Run your test scripts.
  3. Do back (or the backtrace command in your debugger) when mysqld core dumps.
• Try to simulate your application with a Perl script to force MySQL to crash or misbehave.
• Or send a normal bug report. See section 2.3 How to report bugs or problems. But be even more detailed than usual. Since MySQL works for many people it may be that the crash results from something that exists only on your computer (for example, an error that is related to your particular system libraries).

2.4 Guidelines for answering questions on the mailing list

If you consider your answer to have broad interest, you may want to post it to the mailing list instead of replying directly to the individual who asked. Try to make your answer general enough that people other than the original poster may benefit from it. When you post to the list, please make sure that your answer is not a duplication of a previous answer.

Try to summarize the essential part of the question in your reply, but don't feel obliged to quote the whole question.

Please don't post mail messages from your browser with HTML mode turned on! Many users doesn't read mail with a browser!

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