E.1. Debugging a MySQL Server
If you are using some functionality that is very new in MySQL, you
can try to run mysqld with the
--skip-new (which disables all new, potentially
unsafe functionality) or with --safe-mode which
disables a lot of optimization that may cause problems. See
Section A.4.2, “What to Do If MySQL Keeps Crashing”.
If mysqld doesn't want to start, you should
verify that you don't have any my.cnf files
that interfere with your setup! You can check your
my.cnf arguments with mysqld
--print-defaults and avoid using them by starting with
mysqld --no-defaults ....
If mysqld starts to eat up CPU or memory or if
it “hangs,” you can use mysqladmin
processlist status to find out if someone is executing a
query that takes a long time. It may be a good idea to run
mysqladmin -i10 processlist status in some
window if you are experiencing performance problems or problems
when new clients can't connect.
The command mysqladmin debug dumps some
information about locks in use, used memory and query usage to the
MySQL log file. This may help solve some problems. This command
also provides some useful information even if you haven't compiled
MySQL for debugging!
If the problem is that some tables are getting slower and slower
you should try to optimize the table with OPTIMIZE
TABLE or myisamchk. See
Chapter 5, Database Administration. You should also check
the slow queries with EXPLAIN.
You should also read the OS-specific section in this manual for
problems that may be unique to your environment. See
Section 2.12, “Operating System-Specific Notes”.
