MySQL client logging

Let’s learn about client-side logging for MySQL. The mysql client can perform different types of logging of executed statements, and can do so interactively -

UNIX - Logging

On Unix, mysql writes statements to a history file. By default, this file is named .mysql_history in the user's home directory. To specify a different file name, the value of the MYSQL_HISTFILE environment variable must be set.

If the --syslog option is given, mysql will write statements to the system logging tools on various platforms. On Unix, this is called syslog.

Windows - Logging

On Windows, this is called the Windows Event Log. The destination where logged messages appear depends on the system. For example, on Linux, the target is usually the /var/log/messages file.

How does logging happen?

Let’s understand how logging happens -

For each enabled logging target, statement logging happens as described below -

• Statement Will only be logged if executed interactively. When statements are read from a file or pipe, they are non-interactive. Statement logging can be suppressed with the --batch or --execute option.

• If the statement matches an existing pattern, the statement will be ignored and will not be recorded in the "ignore" list.

• mysql records each non-ignored, non-empty statement line separately.

• If a non-ignored statement spans multiple lines and does not contain a terminating delimiter, mysql concatenates the lines to form a complete statement, maps newlines to spaces, and logs result and delimiter.

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