8.20. mysql_explain_log — Use EXPLAIN on Statements in Query Log

mysql_explain_log reads its standard input for query log contents. It uses EXPLAIN to analyze SELECT statements found in the input. UPDATE statements are rewritten to SELECT statements and also analyzed with EXPLAIN. mysql_explain_log then displays a summary of its results.

The results may assist you in determining which queries result in table scans and where it would be beneficial to add indexes to your tables.

Invoke mysql_explain_log like this, where log_file contains all or part of a MySQL query log:

shell> mysql_explain_log [options] < log_file

mysql_explain_log understands the following options:

--help, -?
Display a help message and exit.
--date=YYMMDD, -d YYMMDD
Select entries from the log only for the given date.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
--password=password, -p password
The password to use when connecting to the server.
Specifying a password on the command line should be considered insecure. See Section 5.8.6, “Keeping Your Password Secure”.
--printerror=1, -e 1
Enable error output.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.