Ubuntu Manpage: mysqlindexcheck - Identify Potentially Redundant Table Indexes

Provided by: mysql-utilities_1.6.4-1build1_all

NAME

       mysqlindexcheck - Identify Potentially Redundant Table Indexes

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, only specify the database name. To check a specific
table, name the table in db.table format. It is possible 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 all the columns from idx_b are a prefix of
idx_a. Order and uniqueness count.

· HASH

idx_a and idx_b are redundant if they are duplicates, i.e. if and only if they contain
the same columns in the same order.

· 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 does not count.

To see DROP statements 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 non-primary 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 client command-line
tool.

· 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
client command-line tool.

Note
The --best and --worst lists cannot be printed as SQL statements.
OPTIONS.PP mysqlindexcheck accepts the following command-line options:

· --help

Display a help message and exit.

· --license

Display license information 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.

· --report-indexes, -r

Reports if a table has neither UNIQUE indexes nor a PRIMARY key.

· --server=<source>

Connection information for the server.

To connect to a server, it is necessary to specify connection parameters such as the
user name, host name, password, and either a port or socket. MySQL Utilities provides
a number of ways to supply this information. All of the methods require specifying
your choice via a command-line option such as --server, --master, --slave, etc. The
methods include the following in order of most secure to least secure.

· Use login-paths from your .mylogin.cnf file (encrypted, not visible). Example :
<login-path>[:<port>][:<socket>]

· Use a configuration file (unencrypted, not visible) Note: available in
release-1.5.0. Example : <configuration-file-path>[:<section>]

· Specify the data on the command-line (unencrypted, visible). Example :
<user>[:<passwd>]@<host>[:<port>][:<socket>]

· --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.

· --ssl-ca

The path to a file that contains a list of trusted SSL CAs.

· --ssl-cert

The name of the SSL certificate file to use for establishing a secure connection.

· --ssl-cert

The name of the SSL key file to use for establishing a secure connection.

· --ssl

Specifies if the server connection requires use of SSL. If an encrypted connection
cannot be established, the connection attempt fails. Default setting is 0 (SSL not
required).

· --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 also passed in, limit index statistics to the worst N indexes. The
default value of N is 5, if omitted.
NOTES.PP 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.

The path to the MySQL client tools should be included in the PATH environment variable in
order to use the authentication mechanism with login-paths. This will allow the utility to
use the my_print_defaults tools which is required to read the login-path values from the
login configuration file (.mylogin.cnf). EXAMPLES.PP To check all tables in the employees
database on the local server to see the possible redundant and duplicate indexes, use this
command:

shell> 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)

PERMISSIONS REQUIRED.PP Regarding the privileges needed to run this utility, the user
needs SELECT privilege on the mysql database as well as for the databases which tables are
being checked.

COPYRIGHT

       Copyright © 2006, 2016, Oracle and/or its affiliates. All rights reserved.

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

       This documentation is distributed in the hope that it will be useful, but WITHOUT ANY
       WARRANTY; without even the implied warranty of MERCHANTABILITY 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 the program;
       if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
       Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.

AUTHOR

       Oracle Corporation (http://dev.mysql.com/).

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