MYSQLINDEXCHECK(1)						  MySQL Utilities						MYSQLINDEXCHECK(1)

NAME

       mysqlindexcheck - Check for redundant or duplicate indexes on a list tables or databases

SYNOPSIS

       mysqlindexcheck [options] db[:table] ...

DESCRIPTION

       This utility reads the indexes for one or more tables and identifies duplicate and potentially redundant indexes.

       To check all tables in a database, specify only the database name. To check a specific table, name the table in db.table format. It is pos-
       sible to mix database and table names.

       You can scan tables in any database except the internal databases mysql, INFORMATION_SCHEMA, and performance_schema.

       Depending on the index type, the utility applies the following rules to compare indexes (designated as idx_a and idx_b):

       BTREE  idx_b is redundant to idx_a if and only if the first n columns in idx_b also appear in idx_a. Order and uniqueness count.

       HASH   idx_a and idx_b are duplicates if and only if they contain the same columns in the same order. Uniqueness counts.

       SPATIAL
	      idx_a and idx_b are duplicates if and only if they contain the same column (only one column is permitted).

       FULLTEXT
	      idx_b is redundant to idx_a if and only if all columns in idx_b are included in idx_a. Order counts.

       To see DROP statements to drop redundant indexes, specify the --show-drops option. To examine  the  existing  indexes,  use  the  --verbose
       option, which prints the equivalent CREATE INDEX (or ALTER TABLE for primary keys.

       To  display  the  best or worst nonprimary key indexes for each table, use the --best or --worst option. This causes the output to show the
       best or worst indexes from tables with 10 or more rows.	By default, each option shows five indexes. To override that, provide  an  integer
       value for the option.

       To change the format of the index lists displayed for the --show-indexes, --best, and --worst options, use one of the following values with
       the --format option:

       grid (default)
	      Display output in grid or table format like that of the mysql monitor.

       csv    Display output in comma-separated values format.

       tab    Display output in tab-separated format.

       sql    print SQL statements rather than a list.

       vertical
	      Display output in single-column format like that of the G command for the mysql monitor.

       Note: The --best and --worst lists cannot be printed as SQL statements.

OPTIONS

       mysqlindexcheck accepts the following command-line options:

       --help Display a help message and exit.

       --best[=<N>]
	      If --stats is given, limit index statistics to the best N indexes. The default value of N is 5 if omitted.

       --format=<index_format>, -f<index_format>
	      Specify the index list display format for output produced by --stats. Permitted format values are grid, csv, tab, sql, and vertical.
	      The default is grid.

       --server=<source>
	      Connection information for the server in <user>[:<passwd>]@<host>[:<port>][:<socket>] format.

       --show-drops, -d
	      Display DROP statements for dropping indexes.

       --show-indexes, -i
	      Display indexes for each table.

       --skip, -s
	      Skip tables that do not exist.

       --stats
	      Show index performance statistics.

       --verbose, -v
	      Specify  how  much  information to display. Use this option multiple times to increase the amount of information.  For example, -v =
	      verbose, -vv = more verbose, -vvv = debug.

       --version
	      Display version information and exit.

       --worst[=<N>]
	      If --stats is given, limit index statistics to the worst N indexes. The default value of N is 5 if omitted.

NOTES

       You must provide connection parameters (user, host, password, and so forth) for an account that has the appropriate privileges to read  all
       objects accessed during the operation.

       For  the  --format option, the permitted values are not case sensitive. In addition, values may be specified as any unambiguous prefix of a
       valid value.  For example, --format=g specifies the grid format.  An error occurs if a prefix matches more than one valid value.

EXAMPLES

       To check all tables in the employees database on the local server to see the possible redundant and duplicate indexes, use this command:

       $ mysqlindexcheck --server=root@localhost employees
       # Source on localhost: ... connected.
       # The following indexes are duplicates or redundant 
	 for table employees.dept_emp:
       #
       CREATE INDEX emp_no ON employees.dept_emp (emp_no) USING BTREE
       #     may be redundant or duplicate of:
       ALTER TABLE employees.dept_emp ADD PRIMARY KEY (emp_no, dept_no)
       # The following indexes are duplicates or redundant 
	 for table employees.dept_manager:
       #
       CREATE INDEX emp_no ON employees.dept_manager (emp_no) USING BTREE
       #     may be redundant or duplicate of:
       ALTER TABLE employees.dept_manager ADD PRIMARY KEY (emp_no, dept_no)
       # The following indexes are duplicates or redundant 
	 for table employees.salaries:
       #
       CREATE INDEX emp_no ON employees.salaries (emp_no) USING BTREE
       #     may be redundant or duplicate of:
       ALTER TABLE employees.salaries ADD PRIMARY KEY (emp_no, from_date)
       # The following indexes are duplicates or redundant 
	 for table employees.titles:
       #
       CREATE INDEX emp_no ON employees.titles (emp_no) USING BTREE
       #     may be redundant or duplicate of:
       ALTER TABLE employees.titles ADD PRIMARY KEY (emp_no, title, from_date)

COPYRIGHT

       Copyright (c) 2010, 2012, Oracle and/or its affiliates. All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as  published	by
       the Free Software Foundation; version 2 of the License.

       This  program  is  distributed  in  the	hope  that  it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MER-
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with this program; if not, write to the Free  Software  Foundation,
       Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

AUTHOR

       MySQL Utilities Team

COPYRIGHT

       2010, Oracle and/or its affiliates. All rights reserved.

1.0.3								   May 09, 2012 						MYSQLINDEXCHECK(1)