.\" Automatically generated by Pod::Man 4.11 (Pod::Simple 3.35) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" ======================================================================== .\" .IX Title "PT-DUPLICATE-KEY-CHECKER 1p" .TH PT-DUPLICATE-KEY-CHECKER 1p "2020-08-30" "perl v5.30.3" "User Contributed Perl Documentation" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" pt\-duplicate\-key\-checker \- Find duplicate indexes and foreign keys on MySQL tables. .SH "SYNOPSIS" .IX Header "SYNOPSIS" Usage: pt-duplicate-key-checker [\s-1OPTIONS\s0] [\s-1DSN\s0] .PP pt-duplicate-key-checker examines MySQL tables for duplicate or redundant indexes and foreign keys. Connection options are read from MySQL option files. .PP .Vb 1 \& pt\-duplicate\-key\-checker \-\-host host1 .Ve .SH "RISKS" .IX Header "RISKS" Percona Toolkit is mature, proven in the real world, and well tested, but all database tools can pose a risk to the system and the database server. Before using this tool, please: .IP "\(bu" 4 Read the tool's documentation .IP "\(bu" 4 Review the tool's known \*(L"\s-1BUGS\*(R"\s0 .IP "\(bu" 4 Test the tool on a non-production server .IP "\(bu" 4 Backup your production server and verify the backups .SH "DESCRIPTION" .IX Header "DESCRIPTION" This program examines the output of \s-1SHOW CREATE TABLE\s0 on MySQL tables, and if it finds indexes that cover the same columns as another index in the same order, or cover an exact leftmost prefix of another index, it prints out the suspicious indexes. By default, indexes must be of the same type, so a \&\s-1BTREE\s0 index is not a duplicate of a \s-1FULLTEXT\s0 index, even if they have the same columns. You can override this. .PP It also looks for duplicate foreign keys. A duplicate foreign key covers the same columns as another in the same table, and references the same parent table. .PP The output ends with a short summary that includes an estimate of the total size, in bytes, that the duplicate indexes are using. This is calculated by multiplying the index length by the number of rows in their respective tables. .SH "OPTIONS" .IX Header "OPTIONS" This tool accepts additional command-line arguments. Refer to the \&\*(L"\s-1SYNOPSIS\*(R"\s0 and usage information for details. .IP "\-\-all\-structs" 4 .IX Item "--all-structs" Compare indexes with different structs (\s-1BTREE, HASH,\s0 etc). .Sp By default this is disabled, because a \s-1BTREE\s0 index that covers the same columns as a \s-1FULLTEXT\s0 index is not really a duplicate, for example. .IP "\-\-ask\-pass" 4 .IX Item "--ask-pass" Prompt for a password when connecting to MySQL. .IP "\-\-charset" 4 .IX Item "--charset" short form: \-A; type: string .Sp Default character set. If the value is utf8, sets Perl's binmode on \&\s-1STDOUT\s0 to utf8, passes the mysql_enable_utf8 option to DBD::mysql, and runs \s-1SET NAMES UTF8\s0 after connecting to MySQL. Any other value sets binmode on \s-1STDOUT\s0 without the utf8 layer, and runs \s-1SET NAMES\s0 after connecting to MySQL. .IP "\-\-[no]clustered" 4 .IX Item "--[no]clustered" default: yes .Sp \&\s-1PK\s0 columns appended to secondary key is duplicate. .Sp Detects when a suffix of a secondary key is a leftmost prefix of the primary key, and treats it as a duplicate key. Only detects this condition on storage engines whose primary keys are clustered (currently InnoDB and solidDB). .Sp Clustered storage engines append the primary key columns to the leaf nodes of all secondary keys anyway, so you might consider it redundant to have them appear in the internal nodes as well. Of course, you may also want them in the internal nodes, because just having them at the leaf nodes won't help for some queries. It does help for covering index queries, however. .Sp Here's an example of a key that is considered redundant with this option: .Sp .Vb 2 \& PRIMARY KEY (\`a\`) \& KEY \`b\` (\`b\`,\`a\`) .Ve .Sp The use of such indexes is rather subtle. For example, suppose you have the following query: .Sp .Vb 1 \& SELECT ... WHERE b=1 ORDER BY a; .Ve .Sp This query will do a filesort if we remove the index on \f(CW\*(C`b,a\*(C'\fR. But if we shorten the index on \f(CW\*(C`b,a\*(C'\fR to just \f(CW\*(C`b\*(C'\fR and also remove the \s-1ORDER BY,\s0 the query should return the same results. .Sp The tool suggests shortening duplicate clustered keys by dropping the key and re-adding it without the primary key prefix. The shortened clustered key may still duplicate another key, but the tool cannot currently detect when this happens without being ran a second time to re-check the newly shortened clustered keys. Therefore, if you shorten any duplicate clustered keys, you should run the tool again. .IP "\-\-config" 4 .IX Item "--config" type: Array .Sp Read this comma-separated list of config files; if specified, this must be the first option on the command line. .IP "\-\-databases" 4 .IX Item "--databases" short form: \-d; type: hash .Sp Check only this comma-separated list of databases. .IP "\-\-defaults\-file" 4 .IX Item "--defaults-file" short form: \-F; type: string .Sp Only read mysql options from the given file. You must give an absolute pathname. .IP "\-\-engines" 4 .IX Item "--engines" short form: \-e; type: hash .Sp Check only tables whose storage engine is in this comma-separated list. .IP "\-\-help" 4 .IX Item "--help" Show help and exit. .IP "\-\-host" 4 .IX Item "--host" short form: \-h; type: string .Sp Connect to host. .IP "\-\-ignore\-databases" 4 .IX Item "--ignore-databases" type: Hash .Sp Ignore this comma-separated list of databases. .IP "\-\-ignore\-engines" 4 .IX Item "--ignore-engines" type: Hash .Sp Ignore this comma-separated list of storage engines. .IP "\-\-ignore\-order" 4 .IX Item "--ignore-order" Ignore index order so \s-1KEY\s0(a,b) duplicates \s-1KEY\s0(b,a). .IP "\-\-ignore\-tables" 4 .IX Item "--ignore-tables" type: Hash .Sp Ignore this comma-separated list of tables. Table names may be qualified with the database name. .IP "\-\-key\-types" 4 .IX Item "--key-types" type: string; default: fk .Sp Check for duplicate f=foreign keys, k=keys or fk=both. .IP "\-\-password" 4 .IX Item "--password" short form: \-p; type: string .Sp Password to use when connecting. If password contains commas they must be escaped with a backslash: \*(L"exam\e,ple\*(R" .IP "\-\-pid" 4 .IX Item "--pid" type: string .Sp Create the given \s-1PID\s0 file. The tool won't start if the \s-1PID\s0 file already exists and the \s-1PID\s0 it contains is different than the current \s-1PID.\s0 However, if the \s-1PID\s0 file exists and the \s-1PID\s0 it contains is no longer running, the tool will overwrite the \s-1PID\s0 file with the current \s-1PID.\s0 The \s-1PID\s0 file is removed automatically when the tool exits. .IP "\-\-port" 4 .IX Item "--port" short form: \-P; type: int .Sp Port number to use for connection. .IP "\-\-set\-vars" 4 .IX Item "--set-vars" type: Array .Sp Set the MySQL variables in this comma-separated list of \f(CW\*(C`variable=value\*(C'\fR pairs. .Sp By default, the tool sets: .Sp .Vb 1 \& wait_timeout=10000 .Ve .Sp Variables specified on the command line override these defaults. For example, specifying \f(CW\*(C`\-\-set\-vars wait_timeout=500\*(C'\fR overrides the defaultvalue of \f(CW10000\fR. .Sp The tool prints a warning and continues if a variable cannot be set. .IP "\-\-socket" 4 .IX Item "--socket" short form: \-S; type: string .Sp Socket file to use for connection. .IP "\-\-[no]sql" 4 .IX Item "--[no]sql" default: yes .Sp Print \s-1DROP KEY\s0 statement for each duplicate key. By default an \s-1ALTER TABLE DROP KEY\s0 statement is printed below each duplicate key so that, if you want to remove the duplicate key, you can copy-paste the statement into MySQL. .Sp To disable printing these statements, specify \f(CW\*(C`\-\-no\-sql\*(C'\fR. .IP "\-\-[no]summary" 4 .IX Item "--[no]summary" default: yes .Sp Print summary of indexes at end of output. .IP "\-\-tables" 4 .IX Item "--tables" short form: \-t; type: hash .Sp Check only this comma-separated list of tables. .Sp Table names may be qualified with the database name. .IP "\-\-user" 4 .IX Item "--user" short form: \-u; type: string .Sp User for login if not current user. .IP "\-\-verbose" 4 .IX Item "--verbose" short form: \-v .Sp Output all keys and/or foreign keys found, not just redundant ones. .IP "\-\-version" 4 .IX Item "--version" Show version and exit. .IP "\-\-[no]version\-check" 4 .IX Item "--[no]version-check" default: yes .Sp Check for the latest version of Percona Toolkit, MySQL, and other programs. .Sp This is a standard \*(L"check for updates automatically\*(R" feature, with two additional features. First, the tool checks its own version and also the versions of the following software: operating system, Percona Monitoring and Management (\s-1PMM\s0), MySQL, Perl, MySQL driver for Perl (DBD::mysql), and Percona Toolkit. Second, it checks for and warns about versions with known problems. For example, MySQL 5.5.25 had a critical bug and was re-released as 5.5.25a. .Sp A secure connection to Percona’s Version Check database server is done to perform these checks. Each request is logged by the server, including software version numbers and unique \s-1ID\s0 of the checked system. The \s-1ID\s0 is generated by the Percona Toolkit installation script or when the Version Check database call is done for the first time. .Sp Any updates or known problems are printed to \s-1STDOUT\s0 before the tool's normal output. This feature should never interfere with the normal operation of the tool. .Sp For more information, visit . .SH "DSN OPTIONS" .IX Header "DSN OPTIONS" These \s-1DSN\s0 options are used to create a \s-1DSN.\s0 Each option is given like \&\f(CW\*(C`option=value\*(C'\fR. The options are case-sensitive, so P and p are not the same option. There cannot be whitespace before or after the \f(CW\*(C`=\*(C'\fR and if the value contains whitespace it must be quoted. \s-1DSN\s0 options are comma-separated. See the percona-toolkit manpage for full details. .IP "\(bu" 4 A .Sp dsn: charset; copy: yes .Sp Default character set. .IP "\(bu" 4 D .Sp dsn: database; copy: yes .Sp Default database. .IP "\(bu" 4 F .Sp dsn: mysql_read_default_file; copy: yes .Sp Only read default options from the given file .IP "\(bu" 4 h .Sp dsn: host; copy: yes .Sp Connect to host. .IP "\(bu" 4 p .Sp dsn: password; copy: yes .Sp Password to use when connecting. If password contains commas they must be escaped with a backslash: \*(L"exam\e,ple\*(R" .IP "\(bu" 4 P .Sp dsn: port; copy: yes .Sp Port number to use for connection. .IP "\(bu" 4 S .Sp dsn: mysql_socket; copy: yes .Sp Socket file to use for connection. .IP "\(bu" 4 u .Sp dsn: user; copy: yes .Sp User for login if not current user. .SH "ENVIRONMENT" .IX Header "ENVIRONMENT" The environment variable \f(CW\*(C`PTDEBUG\*(C'\fR enables verbose debugging output to \s-1STDERR.\s0 To enable debugging and capture all output to a file, run the tool like: .PP .Vb 1 \& PTDEBUG=1 pt\-duplicate\-key\-checker ... > FILE 2>&1 .Ve .PP Be careful: debugging output is voluminous and can generate several megabytes of output. .SH "SYSTEM REQUIREMENTS" .IX Header "SYSTEM REQUIREMENTS" You need Perl, \s-1DBI,\s0 DBD::mysql, and some core packages that ought to be installed in any reasonably new version of Perl. .SH "BUGS" .IX Header "BUGS" For a list of known bugs, see . .PP Please report bugs at . Include the following information in your bug report: .IP "\(bu" 4 Complete command-line used to run the tool .IP "\(bu" 4 Tool \*(L"\-\-version\*(R" .IP "\(bu" 4 MySQL version of all servers involved .IP "\(bu" 4 Output from the tool including \s-1STDERR\s0 .IP "\(bu" 4 Input files (log/dump/config files, etc.) .PP If possible, include debugging output by running the tool with \f(CW\*(C`PTDEBUG\*(C'\fR; see \*(L"\s-1ENVIRONMENT\*(R"\s0. .SH "DOWNLOADING" .IX Header "DOWNLOADING" Visit to download the latest release of Percona Toolkit. Or, get the latest release from the command line: .PP .Vb 1 \& wget percona.com/get/percona\-toolkit.tar.gz \& \& wget percona.com/get/percona\-toolkit.rpm \& \& wget percona.com/get/percona\-toolkit.deb .Ve .PP You can also get individual tools from the latest release: .PP .Vb 1 \& wget percona.com/get/TOOL .Ve .PP Replace \f(CW\*(C`TOOL\*(C'\fR with the name of any tool. .SH "AUTHORS" .IX Header "AUTHORS" Baron Schwartz and Daniel Nichter .SH "ABOUT PERCONA TOOLKIT" .IX Header "ABOUT PERCONA TOOLKIT" This tool is part of Percona Toolkit, a collection of advanced command-line tools for MySQL developed by Percona. Percona Toolkit was forked from two projects in June, 2011: Maatkit and Aspersa. Those projects were created by Baron Schwartz and primarily developed by him and Daniel Nichter. Visit to learn about other free, open-source software from Percona. .SH "COPYRIGHT, LICENSE, AND WARRANTY" .IX Header "COPYRIGHT, LICENSE, AND WARRANTY" This program is copyright 2011\-2018 Percona \s-1LLC\s0 and/or its affiliates, 2007\-2011 Baron Schwartz. .PP \&\s-1THIS PROGRAM IS PROVIDED \*(L"AS IS\*(R" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.\s0 .PP This program is free software; you can redistribute it and/or modify it under the terms of the \s-1GNU\s0 General Public License as published by the Free Software Foundation, version 2; \s-1OR\s0 the Perl Artistic License. On \s-1UNIX\s0 and similar systems, you can issue `man perlgpl' or `man perlartistic' to read these licenses. .PP You should have received a copy of the \s-1GNU\s0 General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, \s-1MA\s0 02111\-1307 \s-1USA.\s0 .SH "VERSION" .IX Header "VERSION" pt-duplicate-key-checker 3.2.1 .SH "POD ERRORS" .IX Header "POD ERRORS" Hey! \fBThe above document had some coding errors, which are explained below:\fR .IP "Around line 5602:" 4 .IX Item "Around line 5602:" Non-ASCII character seen before =encoding in 'Percona’s'. Assuming \s-1UTF\-8\s0