- 21.4.1 Debugging a MySQL Server
- 21.4.1.1 Compiling MySQL for Debugging
- 21.4.1.2 Creating Trace Files
- 21.4.1.3 Using pdb to create a Windows crashdump
- 21.4.1.4 Debugging mysqld under gdb
- 21.4.1.5 Using a Stack Trace
- 21.4.1.6 Using Server Logs to Find Causes of Errors in mysqld
- 21.4.1.7 Making a Test Case If You Experience Table Corruption
If you get corrupted tables or if mysqld always fails after some update commands, you can test whether this bug is reproducible by doing the following:
Take down the MySQL daemon (with mysqladmin shutdown).
Make a backup of the tables (to guard against the very unlikely case that the repair does something bad).
Check all tables with myisamchk -s database/*.MYI. Repair any wrong tables with myisamchk -r database/
table.MYI.Make a second backup of the tables.
Remove (or move away) any old log files from the MySQL data directory if you need more space.
Start mysqld with the binary log enabled. If you want to find a query that crashes mysqld, you should start the server with both the general query log enabled as well. See Section 5.2.2, “The General Query Log”, and Section 5.2.3, “The Binary Log”.
When you have gotten a crashed table, stop the
mysqld server.Restore the backup.
Restart the mysqld server without the binary log enabled.
Re-execute the commands with mysqlbinlog binary-log-file | mysql. The binary log is saved in the MySQL database directory with the name
hostname-bin..NNNNNNIf the tables are corrupted again or you can get mysqld to die with the above command, you have found reproducible bug that should be easy to fix! FTP the tables and the binary log to ftp://ftp.mysql.com/pub/mysql/upload/ and report it in our bugs database using the instructions given in Section 1.7, “How to Report Bugs or Problems”. (Please note that the
/pub/mysql/upload/FTP directory is not listable, so you'll not see what you've uploaded in your FTP client.) If you are a support customer, you can use the MySQL Customer Support Center https://support.mysql.com/ to alert the MySQL team about the problem and have it fixed as soon as possible.
You can also use the script mysql_find_rows to just execute some of the update statements if you want to narrow down the problem.
The preceding discussion applies only to RHEL4. The patch is unnecessary for RHEL5.
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