The general query log is a general record of what mysqld is doing. The server writes information to this log when clients connect or disconnect, and it logs each SQL statement received from clients. The general query log can be very useful when you suspect an error in a client and want to know exactly what the client sent to mysqld.

mysqld writes statements to the query log in the order that it receives them, which might differ from the order in which they are executed. This logging order contrasts to the binary log, for which statements are written after they are executed but before any locks are released. (Also, the query log contains all statements, whereas the binary log does not contain statements that only select data.)

To enable the general query log, start mysqld with the --log[=file_name] or -l [file_name] option, and optionally use --log-output to specify the log destination (as described in Section 5.2.1, “Selecting General Query and Slow Query Log Output Destinations”). As of MySQL 6.0.8, --log and -l are deprecated: Use --general_log to enable the general query log, and optionally --general_log_file=file_name to specify a log filename. --general_log takes an optional argument of 1 or 0 to enable or disable the log.

If you specify no filename for the general query log, the default name is host_name.log in the data directory. If you specify a filename that is not an absolute pathname, the server writes the file in the data directory.

When --log or -l is specified, --general_log also may be given to specify the initial general query log state. With no argument or an argument of 0, the option disables the log. If omitted or given with an argument of 1, the option enables the log.

For runtime control of the general query log, use the global general_log and general_log_file system variables. Set general_log to 0 (or OFF) to disable the log or to 1 (or ON) to enable it. Set general_log_file to specify the name of the log file. If a log file already is open, it is closed and the new file is opened.

When the general query log is enabled, output is written to any destinations specified by the --log-output option or log_output system variable. If you enable the log, the server opens the log file and writes startup messages to it. However, logging of queries to the file does not occur unless the FILE log destination is selected. If the destination is NONE, no queries are written even if the general log is enabled. Setting the log filename has no effect on logging if the log destination value does not contain FILE.

Server restarts and log flushing do not cause a new general query log file to be generated (although flushing closes and reopens it). On Unix, you can rename the file and create a new one by using the following commands:

shell> mv host_name.log host_name-old.log
shell> mysqladmin flush-logs
shell> cp host_name-old.log backup-directory
shell> rm host_name-old.log

On Windows, you can rename the general query log or slow query log while the server has it open. You cannot rename the error log file while the server has it open. You must stop the server and rename the file, and then restart the server to create a new log file. However, a stop and restart can be avoided by using FLUSH LOGS, which causes the server to rename the error log with an -old suffix and open a new error log.

You can disable the general query log at runtime:

SET GLOBAL general_log = 'OFF';

With the log disabled, rename the log file externally; for example, from the command line. Then enable the log again:

SET GLOBAL general_log = 'ON';

This method works on any platform and does not require a server restart.

The session sql_log_off variable can be set to ON or OFF to disable or enable general query logging for the current connection.