MySQLTuner adjust your MySQL database

MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability. Within seconds, it will display statistics about your MySQL installation and the areas where it can be improved.

It's key to remember that MySQLTuner is a script which can assist you with your server, but it is not the solution to a badly performing MySQL server. The best performance gains come from a thorough review of the queries sent to the server, and an evaluation of the MySQL server itself. A qualified developer in your application's programming or scripting language should be able to work with a MySQL database administrator to find improvements for your server. Once the server and application are optimized well, you may need to consider hardware upgrades to the physical server itself.
This is a really useful tool for helping to optimize MySQL performance.Understanding the various my.cnf variables and how they affect performance can seem really complicated but this tool takes some of the pain away and makes it easier to understand the effects of each variable.It is especially useful to be able to see the global memory usage, memory usage per thread and the maximum possible memory usage — that is really valuable information that is otherwise complex to calculate.

Run MySQLTuner in Debian

Copy and past the below code and save it as mysqltuner.pl using nano 😉

#!/usr/bin/perl -w
# mysqltuner.pl – Version 1.2.0
# High Performance MySQL Tuning Script
# Copyright (C) 2006-2011 Major Hayden – major@mhtx.net
#
# For the latest updates, please visit http://mysqltuner.com/
# Git repository available at http://github.com/rackerhacker/MySQLTuner-perl
#
# 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, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
#
# This project would not be possible without help from:
# Matthew Montgomery Paul Kehrer Dave Burgess
# Jonathan Hinds Mike Jackson Nils Breunese
# Shawn Ashlee Luuk Vosslamber Ville Skytta
# Trent Hornibrook Jason Gill Mark Imbriaco
# Greg Eden Aubin Galinotti Giovanni Bechis
# Bill Bradford Ryan Novosielski Michael Scheidell
# Blair Christensen Hans du Plooy Victor Trac
# Everett Barnes Tom Krouper Gary Barrueto
# Simon Greenaway Adam Stein Isart Montane
# Baptiste M.
#
# Inspired by Matthew Montgomery's tuning-primer.sh script:
# http://forge.mysql.com/projects/view.php?id=44
#
use strict;
use warnings;
use diagnostics;
use File::Spec;
use Getopt::Long;

# Set up a few variables for use in the script
my $tunerversion = "1.2.0";
my (@adjvars, @generalrec);

# Set defaults
my %opt = (
"nobad" => 0,
"nogood" => 0,
"noinfo" => 0,
"nocolor" => 0,
"forcemem" => 0,
"forceswap" => 0,
"host" => 0,
"socket" => 0,
"port" => 0,
"user" => 0,
"pass" => 0,
"skipsize" => 0,
"checkversion" => 0,
);

# Gather the options from the command line
GetOptions(\%opt,
'nobad',
'nogood',
'noinfo',
'nocolor',
'forcemem=i',
'forceswap=i',
'host=s',
'socket=s',
'port=i',
'user=s',
'pass=s',
'skipsize',
'checkversion',
'help',
);

if (defined $opt{'help'} && $opt{'help'} == 1) { usage(); }

sub usage {
# Shown with –help option passed
print "\n".
" MySQLTuner $tunerversion – MySQL High Performance Tuning Script\n".
" Bug reports, feature requests, and downloads at http://mysqltuner.com/\n".
" Maintained by Major Hayden (major\@mhtx.net) – Licensed under GPL\n".
"\n".
" Important Usage Guidelines:\n".
" To run the script with the default options, run the script without arguments\n".
" Allow MySQL server to run for at least 24-48 hours before trusting suggestions\n".
" Some routines may require root level privileges (script will provide warnings)\n".
" You must provide the remote server's total memory when connecting to other servers\n".
"\n".
" Connection and Authentication\n".
" –host <hostname> Connect to a remote host to perform tests (default: localhost)\n".
" –socket <socket> Use a different socket for a local connection\n".
" –port <port> Port to use for connection (default: 3306)\n".
" –user <username> Username to use for authentication\n".
" –pass <password> Password to use for authentication\n".
"\n".
" Performance and Reporting Options\n".
" –skipsize Don't enumerate tables and their types/sizes (default: on)\n".
" (Recommended for servers with many tables)\n".
" –checkversion Check for updates to MySQLTuner (default: don't check)\n".
" –forcemem <size> Amount of RAM installed in megabytes\n".
" –forceswap <size> Amount of swap memory configured in megabytes\n".
"\n".
" Output Options:\n".
" –nogood Remove OK responses\n".
" –nobad Remove negative/suggestion responses\n".
" –noinfo Remove informational responses\n".
" –nocolor Don't print output in color\n".
"\n";
exit;
}

my $devnull = File::Spec->devnull();

# Setting up the colors for the print styles
my $good = ($opt{nocolor} == 0)? "[\e[0;32mOK\e[0m]" : "[OK]" ;
my $bad = ($opt{nocolor} == 0)? "[\e[0;31m!!\e[0m]" : "[!!]" ;
my $info = ($opt{nocolor} == 0)? "[\e[0;34m–\e[0m]" : "[–]" ;

# Functions that handle the print styles
sub goodprint { print $good." ".$_[0] unless ($opt{nogood} == 1); }
sub infoprint { print $info." ".$_[0] unless ($opt{noinfo} == 1); }
sub badprint { print $bad." ".$_[0] unless ($opt{nobad} == 1); }
sub redwrap { return ($opt{nocolor} == 0)? "\e[0;31m".$_[0]."\e[0m" : $_[0] ; }
sub greenwrap { return ($opt{nocolor} == 0)? "\e[0;32m".$_[0]."\e[0m" : $_[0] ; }

# Calculates the parameter passed in bytes, and then rounds it to one decimal place
sub hr_bytes {
my $num = shift;
if ($num >= (1024**3)) { #GB
return sprintf("%.1f",($num/(1024**3)))."G";
} elsif ($num >= (1024**2)) { #MB
return sprintf("%.1f",($num/(1024**2)))."M";
} elsif ($num >= 1024) { #KB
return sprintf("%.1f",($num/1024))."K";
} else {
return $num."B";
}
}

# Calculates the parameter passed in bytes, and then rounds it to the nearest integer
sub hr_bytes_rnd {
my $num = shift;
if ($num >= (1024**3)) { #GB
return int(($num/(1024**3)))."G";
} elsif ($num >= (1024**2)) { #MB
return int(($num/(1024**2)))."M";
} elsif ($num >= 1024) { #KB
return int(($num/1024))."K";
} else {
return $num."B";
}
}

# Calculates the parameter passed to the nearest power of 1000, then rounds it to the nearest integer
sub hr_num {
my $num = shift;
if ($num >= (1000**3)) { # Billions
return int(($num/(1000**3)))."B";
} elsif ($num >= (1000**2)) { # Millions
return int(($num/(1000**2)))."M";
} elsif ($num >= 1000) { # Thousands
return int(($num/1000))."K";
} else {
return $num;
}
}

# Calculates uptime to display in a more attractive form
sub pretty_uptime {
my $uptime = shift;
my $seconds = $uptime % 60;
my $minutes = int(($uptime % 3600) / 60);
my $hours = int(($uptime % 86400) / (3600));
my $days = int($uptime / (86400));
my $uptimestring;
if ($days > 0) {
$uptimestring = "${days}d ${hours}h ${minutes}m ${seconds}s";
} elsif ($hours > 0) {
$uptimestring = "${hours}h ${minutes}m ${seconds}s";
} elsif ($minutes > 0) {
$uptimestring = "${minutes}m ${seconds}s";
} else {
$uptimestring = "${seconds}s";
}
return $uptimestring;
}

# Retrieves the memory installed on this machine
my ($physical_memory,$swap_memory,$duflags);
sub os_setup {
sub memerror {
badprint "Unable to determine total memory/swap; use '–forcemem' and '–forceswap'\n";
exit;
}
my $os = `uname`;
$duflags = ($os =~ /Linux/) ? '-b' : '';
if ($opt{'forcemem'} > 0) {
$physical_memory = $opt{'forcemem'} * 1048576;
infoprint "Assuming $opt{'forcemem'} MB of physical memory\n";
if ($opt{'forceswap'} > 0) {
$swap_memory = $opt{'forceswap'} * 1048576;
infoprint "Assuming $opt{'forceswap'} MB of swap space\n";
} else {
$swap_memory = 0;
badprint "Assuming 0 MB of swap space (use –forceswap to specify)\n";
}
} else {
if ($os =~ /Linux/) {
$physical_memory = `free -b | grep Mem | awk '{print \$2}'` or memerror;
$swap_memory = `free -b | grep Swap | awk '{print \$2}'` or memerror;
} elsif ($os =~ /Darwin/) {
$physical_memory = `sysctl -n hw.memsize` or memerror;
$swap_memory = `sysctl -n vm.swapusage | awk '{print \$3}' | sed 's/\..*\$//'` or memerror;
} elsif ($os =~ /NetBSD|OpenBSD/) {
$physical_memory = `sysctl -n hw.physmem` or memerror;
if ($physical_memory < 0) {
$physical_memory = `sysctl -n hw.physmem64` or memerror;
}
$swap_memory = `swapctl -l | grep '^/' | awk '{ s+= \$2 } END { print s }'` or memerror;
} elsif ($os =~ /BSD/) {
$physical_memory = `sysctl -n hw.realmem`;
$swap_memory = `swapinfo | grep '^/' | awk '{ s+= \$2 } END { print s }'`;
} elsif ($os =~ /SunOS/) {
$physical_memory = `/usr/sbin/prtconf | grep Memory | cut -f 3 -d ' '` or memerror;
chomp($physical_memory);
$physical_memory = $physical_memory*1024*1024;
} elsif ($os =~ /AIX/) {
$physical_memory = `lsattr -El sys0 | grep realmem | awk '{print \$2}'` or memerror;
chomp($physical_memory);
$physical_memory = $physical_memory*1024;
$swap_memory = `lsps -as | awk -F"(MB| +)" '/MB /{print \$2}'` or memerror;
chomp($swap_memory);
$swap_memory = $swap_memory*1024*1024;
}
}
chomp($physical_memory);
}

# Checks to see if a MySQL login is possible
my ($mysqllogin,$doremote,$remotestring);
sub mysql_setup {
$doremote = 0;
$remotestring = '';
my $command = `which mysqladmin`;
chomp($command);
if (! -e $command) {
badprint "Unable to find mysqladmin in your \$PATH. Is MySQL installed?\n";
exit;
}
# Are we being asked to connect via a socket?
if ($opt{socket} ne 0) {
$remotestring = " -S $opt{socket}";
}
# Are we being asked to connect to a remote server?
if ($opt{host} ne 0) {
chomp($opt{host});
$opt{port} = ($opt{port} eq 0)? 3306 : $opt{port} ;
# If we're doing a remote connection, but forcemem wasn't specified, we need to exit
if ($opt{'forcemem'} eq 0) {
badprint "The –forcemem option is required for remote connections\n";
exit;
}
infoprint "Performing tests on $opt{host}:$opt{port}\n";
$remotestring = " -h $opt{host} -P $opt{port}";
$doremote = 1;
}
# Did we already get a username and password passed on the command line?
if ($opt{user} ne 0 and $opt{pass} ne 0) {
$mysqllogin = "-u $opt{user} -p'$opt{pass}'".$remotestring;
my $loginstatus = `mysqladmin ping $mysqllogin 2>&1`;
if ($loginstatus =~ /mysqld is alive/) {
goodprint "Logged in using credentials passed on the command line\n";
return 1;
} else {
badprint "Attempted to use login credentials, but they were invalid\n";
exit 0;
}
}
if ( -r "/etc/psa/.psa.shadow" and $doremote == 0 ) {
# It's a Plesk box, use the available credentials
$mysqllogin = "-u admin -p`cat /etc/psa/.psa.shadow`";
my $loginstatus = `mysqladmin ping $mysqllogin 2>&1`;
unless ($loginstatus =~ /mysqld is alive/) {
badprint "Attempted to use login credentials from Plesk, but they failed.\n";
exit 0;
}
} elsif ( -r "/etc/mysql/debian.cnf" and $doremote == 0 ){
# We have a debian maintenance account, use it
$mysqllogin = "–defaults-file=/etc/mysql/debian.cnf";
my $loginstatus = `mysqladmin $mysqllogin ping 2>&1`;
if ($loginstatus =~ /mysqld is alive/) {
goodprint "Logged in using credentials from debian maintenance account.\n";
return 1;
} else {
badprint "Attempted to use login credentials from debian maintenance account, but they failed.\n";
exit 0;
}
} else {
# It's not Plesk or debian, we should try a login
my $loginstatus = `mysqladmin $remotestring ping 2>&1`;
if ($loginstatus =~ /mysqld is alive/) {
# Login went just fine
$mysqllogin = " $remotestring ";
# Did this go well because of a .my.cnf file or is there no password set?
my $userpath = `printenv HOME`;
if (length($userpath) > 0) {
chomp($userpath);
}
unless ( -e "${userpath}/.my.cnf" ) {
badprint "Successfully authenticated with no password – SECURITY RISK!\n";
}
return 1;
} else {
print STDERR "Please enter your MySQL administrative login: ";
my $name = <>;
print STDERR "Please enter your MySQL administrative password: ";
system("stty -echo >$devnull 2>&1");
my $password = <>;
system("stty echo >$devnull 2>&1");
chomp($password);
chomp($name);
$mysqllogin = "-u $name";
if (length($password) > 0) {
$mysqllogin .= " -p'$password'";
}
$mysqllogin .= $remotestring;
my $loginstatus = `mysqladmin ping $mysqllogin 2>&1`;
if ($loginstatus =~ /mysqld is alive/) {
print STDERR "\n";
if (! length($password)) {
# Did this go well because of a .my.cnf file or is there no password set?
my $userpath = `ls -d ~`;
chomp($userpath);
unless ( -e "$userpath/.my.cnf" ) {
badprint "Successfully authenticated with no password – SECURITY RISK!\n";
}
}
return 1;
} else {
print "\n".$bad." Attempted to use login credentials, but they were invalid.\n";
exit 0;
}
exit 0;
}
}
}

# Populates all of the variable and status hashes
my (%mystat,%myvar,$dummyselect);
sub get_all_vars {
# We need to initiate at least one query so that our data is useable
$dummyselect = `mysql $mysqllogin -Bse "SELECT VERSION();"`;
my @mysqlvarlist = `mysql $mysqllogin -Bse "SHOW /*!50000 GLOBAL */ VARIABLES;"`;
foreach my $line (@mysqlvarlist) {
$line =~ /([a-zA-Z_]*)\s*(.*)/;
$myvar{$1} = $2;
}
my @mysqlstatlist = `mysql $mysqllogin -Bse "SHOW /*!50000 GLOBAL */ STATUS;"`;
foreach my $line (@mysqlstatlist) {
$line =~ /([a-zA-Z_]*)\s*(.*)/;
$mystat{$1} = $2;
}
# Workaround for MySQL bug #59393 wrt. ignore-builtin-innodb
if (($myvar{'ignore_builtin_innodb'} || "") eq "ON") {
$myvar{'have_innodb'} = "NO";
}
# have_* for engines is deprecated and will be removed in MySQL 5.6;
# check SHOW ENGINES and set corresponding old style variables.
# Also works around MySQL bug #59393 wrt. skip-innodb
my @mysqlenginelist = `mysql $mysqllogin -Bse "SHOW ENGINES;" 2>$devnull`;
foreach my $line (@mysqlenginelist) {
if ($line =~ /^([a-zA-Z_]+)\s+(\S+)/) {
my $engine = lc($1);
if ($engine eq "federated" || $engine eq "blackhole") {
$engine .= "_engine";
} elsif ($engine eq "berkeleydb") {
$engine = "bdb";
}
my $val = ($2 eq "DEFAULT") ? "YES" : $2;
$myvar{"have_$engine"} = $val;
}
}
}

sub security_recommendations {
print "\n——– Security Recommendations ——————————————-\n";
my @mysqlstatlist = `mysql $mysqllogin -Bse "SELECT CONCAT(user, '\@', host) FROM mysql.user WHERE password = '' OR password IS NULL;"`;
if (@mysqlstatlist) {
foreach my $line (sort @mysqlstatlist) {
chomp($line);
badprint "User '".$line."' has no password set.\n";
}
} else {
goodprint "All database users have passwords assigned\n";
}
}

sub get_replication_status {
my $slave_status = `mysql $mysqllogin -Bse "show slave status\\G"`;
my ($io_running) = ($slave_status =~ /slave_io_running\S*\s+(\S+)/i);
my ($sql_running) = ($slave_status =~ /slave_sql_running\S*\s+(\S+)/i);
if ($io_running eq 'Yes' && $sql_running eq 'Yes') {
if ($myvar{'read_only'} eq 'OFF') {
badprint "This replication slave is running with the read_only option disabled.";
} else {
goodprint "This replication slave is running with the read_only option enabled.";
}
}
}

# Checks for updates to MySQLTuner
sub validate_tuner_version {
print "\n——– General Statistics ————————————————–\n";
if ($opt{checkversion} eq 0) {
infoprint "Skipped version check for MySQLTuner script\n";
return;
}
my $update;
my $url = "http://mysqltuner.com/versioncheck.php?v=$tunerversion";
if (-e "/usr/bin/curl") {
$update = `/usr/bin/curl –connect-timeout 5 '$url' 2>$devnull`;
chomp($update);
} elsif (-e "/usr/bin/wget") {
$update = `/usr/bin/wget -e timestamping=off -T 5 -O – '$url' 2>$devnull`;
chomp($update);
}
if ($update eq 1) {
badprint "There is a new version of MySQLTuner available\n";
} elsif ($update eq 0) {
goodprint "You have the latest version of MySQLTuner\n";
} else {
infoprint "Unable to check for the latest MySQLTuner version\n";
}
}

# Checks for supported or EOL'ed MySQL versions
my ($mysqlvermajor,$mysqlverminor);
sub validate_mysql_version {
($mysqlvermajor,$mysqlverminor) = $myvar{'version'} =~ /(\d)\.(\d)/;
if (!mysql_version_ge(5)) {
badprint "Your MySQL version ".$myvar{'version'}." is EOL software! Upgrade soon!\n";
} elsif (mysql_version_ge(6)) {
badprint "Currently running unsupported MySQL version ".$myvar{'version'}."\n";
} else {
goodprint "Currently running supported MySQL version ".$myvar{'version'}."\n";
}
}

# Checks if MySQL version is greater than equal to (major, minor)
sub mysql_version_ge {
my ($maj, $min) = @_;
return $mysqlvermajor > $maj || ($mysqlvermajor == $maj && $mysqlverminor >= ($min || 0));
}

# Checks for 32-bit boxes with more than 2GB of RAM
my ($arch);
sub check_architecture {
if ($doremote eq 1) { return; }
if (`uname` =~ /SunOS/ && `isainfo -b` =~ /64/) {
$arch = 64;
goodprint "Operating on 64-bit architecture\n";
} elsif (`uname` !~ /SunOS/ && `uname -m` =~ /64/) {
$arch = 64;
goodprint "Operating on 64-bit architecture\n";
} elsif (`uname` =~ /AIX/ && `bootinfo -K` =~ /64/) {
$arch = 64;
goodprint "Operating on 64-bit architecture\n";
} else {
$arch = 32;
if ($physical_memory > 2147483648) {
badprint "Switch to 64-bit OS – MySQL cannot currently use all of your RAM\n";
} else {
goodprint "Operating on 32-bit architecture with less than 2GB RAM\n";
}
}
}

# Start up a ton of storage engine counts/statistics
my (%enginestats,%enginecount,$fragtables);
sub check_storage_engines {
if ($opt{skipsize} eq 1) {
print "\n——– Storage Engine Statistics ——————————————-\n";
infoprint "Skipped due to –skipsize option\n";
return;
}
print "\n——– Storage Engine Statistics ——————————————-\n";
infoprint "Status: ";
my $engines;
$engines .= (defined $myvar{'have_archive'} && $myvar{'have_archive'} eq "YES")? greenwrap "+Archive " : redwrap "-Archive " ;
$engines .= (defined $myvar{'have_bdb'} && $myvar{'have_bdb'} eq "YES")? greenwrap "+BDB " : redwrap "-BDB " ;
$engines .= (defined $myvar{'have_federated_engine'} && $myvar{'have_federated_engine'} eq "YES")? greenwrap "+Federated " : redwrap "-Federated " ;
$engines .= (defined $myvar{'have_innodb'} && $myvar{'have_innodb'} eq "YES")? greenwrap "+InnoDB " : redwrap "-InnoDB " ;
$engines .= (defined $myvar{'have_isam'} && $myvar{'have_isam'} eq "YES")? greenwrap "+ISAM " : redwrap "-ISAM " ;
$engines .= (defined $myvar{'have_ndbcluster'} && $myvar{'have_ndbcluster'} eq "YES")? greenwrap "+NDBCluster " : redwrap "-NDBCluster " ;
print "$engines\n";
if (mysql_version_ge(5)) {
# MySQL 5 servers can have table sizes calculated quickly from information schema
my @templist = `mysql $mysqllogin -Bse "SELECT ENGINE,SUM(DATA_LENGTH),COUNT(ENGINE) FROM information_schema.TABLES WHERE TABLE_SCHEMA NOT IN ('information_schema','mysql') AND ENGINE IS NOT NULL GROUP BY ENGINE ORDER BY ENGINE ASC;"`;
foreach my $line (@templist) {
my ($engine,$size,$count);
($engine,$size,$count) = $line =~ /([a-zA-Z_]*)\s+(\d+)\s+(\d+)/;
if (!defined($size)) { next; }
$enginestats{$engine} = $size;
$enginecount{$engine} = $count;
}
$fragtables = `mysql $mysqllogin -Bse "SELECT COUNT(TABLE_NAME) FROM information_schema.TABLES WHERE TABLE_SCHEMA NOT IN ('information_schema','mysql') AND Data_free > 0 AND NOT ENGINE='MEMORY';"`;
chomp($fragtables);
} else {
# MySQL < 5 servers take a lot of work to get table sizes
my @tblist;
# Now we build a database list, and loop through it to get storage engine stats for tables
my @dblist = `mysql $mysqllogin -Bse "SHOW DATABASES"`;
foreach my $db (@dblist) {
chomp($db);
if ($db eq "information_schema") { next; }
my @ixs = (1, 6, 9);
if (!mysql_version_ge(4, 1)) {
# MySQL 3.23/4.0 keeps Data_Length in the 5th (0-based) column
@ixs = (1, 5, 8);
}
push(@tblist, map { [ (split)[@ixs] ] } `mysql $mysqllogin -Bse "SHOW TABLE STATUS FROM \\\`$db\\\`"`);
}
# Parse through the table list to generate storage engine counts/statistics
$fragtables = 0;
foreach my $tbl (@tblist) {
my ($engine, $size, $datafree) = @$tbl;
if (defined $enginestats{$engine}) {
$enginestats{$engine} += $size;
$enginecount{$engine} += 1;
} else {
$enginestats{$engine} = $size;
$enginecount{$engine} = 1;
}
if ($datafree > 0) {
$fragtables++;
}
}
}
while (my ($engine,$size) = each(%enginestats)) {
infoprint "Data in $engine tables: ".hr_bytes_rnd($size)." (Tables: ".$enginecount{$engine}.")"."\n";
}
# If the storage engine isn't being used, recommend it to be disabled
if (!defined $enginestats{'InnoDB'} && defined $myvar{'have_innodb'} && $myvar{'have_innodb'} eq "YES") {
badprint "InnoDB is enabled but isn't being used\n";
push(@generalrec,"Add skip-innodb to MySQL configuration to disable InnoDB");
}
if (!defined $enginestats{'BerkeleyDB'} && defined $myvar{'have_bdb'} && $myvar{'have_bdb'} eq "YES") {
badprint "BDB is enabled but isn't being used\n";
push(@generalrec,"Add skip-bdb to MySQL configuration to disable BDB");
}
if (!defined $enginestats{'ISAM'} && defined $myvar{'have_isam'} && $myvar{'have_isam'} eq "YES") {
badprint "ISAM is enabled but isn't being used\n";
push(@generalrec,"Add skip-isam to MySQL configuration to disable ISAM (MySQL > 4.1.0)");
}
# Fragmented tables
if ($fragtables > 0) {
badprint "Total fragmented tables: $fragtables\n";
push(@generalrec,"Run OPTIMIZE TABLE to defragment tables for better performance");
} else {
goodprint "Total fragmented tables: $fragtables\n";
}
}

my %mycalc;
sub calculations {
if ($mystat{'Questions'} < 1) {
badprint "Your server has not answered any queries – cannot continue…";
exit 0;
}
# Per-thread memory
if (mysql_version_ge(4)) {
$mycalc{'per_thread_buffers'} = $myvar{'read_buffer_size'} + $myvar{'read_rnd_buffer_size'} + $myvar{'sort_buffer_size'} + $myvar{'thread_stack'} + $myvar{'join_buffer_size'};
} else {
$mycalc{'per_thread_buffers'} = $myvar{'record_buffer'} + $myvar{'record_rnd_buffer'} + $myvar{'sort_buffer'} + $myvar{'thread_stack'} + $myvar{'join_buffer_size'};
}
$mycalc{'total_per_thread_buffers'} = $mycalc{'per_thread_buffers'} * $myvar{'max_connections'};
$mycalc{'max_total_per_thread_buffers'} = $mycalc{'per_thread_buffers'} * $mystat{'Max_used_connections'};

# Server-wide memory
$mycalc{'max_tmp_table_size'} = ($myvar{'tmp_table_size'} > $myvar{'max_heap_table_size'}) ? $myvar{'max_heap_table_size'} : $myvar{'tmp_table_size'} ;
$mycalc{'server_buffers'} = $myvar{'key_buffer_size'} + $mycalc{'max_tmp_table_size'};
$mycalc{'server_buffers'} += (defined $myvar{'innodb_buffer_pool_size'}) ? $myvar{'innodb_buffer_pool_size'} : 0 ;
$mycalc{'server_buffers'} += (defined $myvar{'innodb_additional_mem_pool_size'}) ? $myvar{'innodb_additional_mem_pool_size'} : 0 ;
$mycalc{'server_buffers'} += (defined $myvar{'innodb_log_buffer_size'}) ? $myvar{'innodb_log_buffer_size'} : 0 ;
$mycalc{'server_buffers'} += (defined $myvar{'query_cache_size'}) ? $myvar{'query_cache_size'} : 0 ;

# Global memory
$mycalc{'max_used_memory'} = $mycalc{'server_buffers'} + $mycalc{"max_total_per_thread_buffers"};
$mycalc{'total_possible_used_memory'} = $mycalc{'server_buffers'} + $mycalc{'total_per_thread_buffers'};
$mycalc{'pct_physical_memory'} = int(($mycalc{'total_possible_used_memory'} * 100) / $physical_memory);

# Slow queries
$mycalc{'pct_slow_queries'} = int(($mystat{'Slow_queries'}/$mystat{'Questions'}) * 100);

# Connections
$mycalc{'pct_connections_used'} = int(($mystat{'Max_used_connections'}/$myvar{'max_connections'}) * 100);
$mycalc{'pct_connections_used'} = ($mycalc{'pct_connections_used'} > 100) ? 100 : $mycalc{'pct_connections_used'} ;

# Key buffers
if (mysql_version_ge(4, 1)) {
$mycalc{'pct_key_buffer_used'} = sprintf("%.1f",(1 – (($mystat{'Key_blocks_unused'} * $myvar{'key_cache_block_size'}) / $myvar{'key_buffer_size'})) * 100);
}
if ($mystat{'Key_read_requests'} > 0) {
$mycalc{'pct_keys_from_mem'} = sprintf("%.1f",(100 – (($mystat{'Key_reads'} / $mystat{'Key_read_requests'}) * 100)));
} else {
$mycalc{'pct_keys_from_mem'} = 0;
}
if ($doremote eq 0 and !mysql_version_ge(5)) {
my $size = 0;
$size += (split)[0] for `find $myvar{'datadir'} -name "*.MYI" 2>&1 | xargs du -L $duflags 2>&1`;
$mycalc{'total_myisam_indexes'} = $size;
} elsif (mysql_version_ge(5)) {
$mycalc{'total_myisam_indexes'} = `mysql $mysqllogin -Bse "SELECT IFNULL(SUM(INDEX_LENGTH),0) FROM information_schema.TABLES WHERE TABLE_SCHEMA NOT IN ('information_schema') AND ENGINE = 'MyISAM';"`;
}
if (defined $mycalc{'total_myisam_indexes'} and $mycalc{'total_myisam_indexes'} == 0) {
$mycalc{'total_myisam_indexes'} = "fail";
} elsif (defined $mycalc{'total_myisam_indexes'}) {
chomp($mycalc{'total_myisam_indexes'});
}

# Query cache
if (mysql_version_ge(4)) {
$mycalc{'query_cache_efficiency'} = sprintf("%.1f",($mystat{'Qcache_hits'} / ($mystat{'Com_select'} + $mystat{'Qcache_hits'})) * 100);
if ($myvar{'query_cache_size'}) {
$mycalc{'pct_query_cache_used'} = sprintf("%.1f",100 – ($mystat{'Qcache_free_memory'} / $myvar{'query_cache_size'}) * 100);
}
if ($mystat{'Qcache_lowmem_prunes'} == 0) {
$mycalc{'query_cache_prunes_per_day'} = 0;
} else {
$mycalc{'query_cache_prunes_per_day'} = int($mystat{'Qcache_lowmem_prunes'} / ($mystat{'Uptime'}/86400));
}
}

# Sorting
$mycalc{'total_sorts'} = $mystat{'Sort_scan'} + $mystat{'Sort_range'};
if ($mycalc{'total_sorts'} > 0) {
$mycalc{'pct_temp_sort_table'} = int(($mystat{'Sort_merge_passes'} / $mycalc{'total_sorts'}) * 100);
}

# Joins
$mycalc{'joins_without_indexes'} = $mystat{'Select_range_check'} + $mystat{'Select_full_join'};
$mycalc{'joins_without_indexes_per_day'} = int($mycalc{'joins_without_indexes'} / ($mystat{'Uptime'}/86400));

# Temporary tables
if ($mystat{'Created_tmp_tables'} > 0) {
if ($mystat{'Created_tmp_disk_tables'} > 0) {
$mycalc{'pct_temp_disk'} = int(($mystat{'Created_tmp_disk_tables'} / ($mystat{'Created_tmp_tables'} + $mystat{'Created_tmp_disk_tables'})) * 100);
} else {
$mycalc{'pct_temp_disk'} = 0;
}
}

# Table cache
if ($mystat{'Opened_tables'} > 0) {
$mycalc{'table_cache_hit_rate'} = int($mystat{'Open_tables'}*100/$mystat{'Opened_tables'});
} else {
$mycalc{'table_cache_hit_rate'} = 100;
}

# Open files
if ($myvar{'open_files_limit'} > 0) {
$mycalc{'pct_files_open'} = int($mystat{'Open_files'}*100/$myvar{'open_files_limit'});
}

# Table locks
if ($mystat{'Table_locks_immediate'} > 0) {
if ($mystat{'Table_locks_waited'} == 0) {
$mycalc{'pct_table_locks_immediate'} = 100;
} else {
$mycalc{'pct_table_locks_immediate'} = int($mystat{'Table_locks_immediate'}*100/($mystat{'Table_locks_waited'} + $mystat{'Table_locks_immediate'}));
}
}

# Thread cache
$mycalc{'thread_cache_hit_rate'} = int(100 – (($mystat{'Threads_created'} / $mystat{'Connections'}) * 100));

# Other
if ($mystat{'Connections'} > 0) {
$mycalc{'pct_aborted_connections'} = int(($mystat{'Aborted_connects'}/$mystat{'Connections'}) * 100);
}
if ($mystat{'Questions'} > 0) {
$mycalc{'total_reads'} = $mystat{'Com_select'};
$mycalc{'total_writes'} = $mystat{'Com_delete'} + $mystat{'Com_insert'} + $mystat{'Com_update'} + $mystat{'Com_replace'};
if ($mycalc{'total_reads'} == 0) {
$mycalc{'pct_reads'} = 0;
$mycalc{'pct_writes'} = 100;
} else {
$mycalc{'pct_reads'} = int(($mycalc{'total_reads'}/($mycalc{'total_reads'}+$mycalc{'total_writes'})) * 100);
$mycalc{'pct_writes'} = 100-$mycalc{'pct_reads'};
}
}

# InnoDB
if ($myvar{'have_innodb'} eq "YES") {
$mycalc{'innodb_log_size_pct'} = ($myvar{'innodb_log_file_size'} * 100 / $myvar{'innodb_buffer_pool_size'});
}
}

sub mysql_stats {
print "\n——– Performance Metrics ————————————————-\n";
# Show uptime, queries per second, connections, traffic stats
my $qps;
if ($mystat{'Uptime'} > 0) { $qps = sprintf("%.3f",$mystat{'Questions'}/$mystat{'Uptime'}); }
if ($mystat{'Uptime'} < 86400) { push(@generalrec,"MySQL started within last 24 hours – recommendations may be inaccurate"); }
infoprint "Up for: ".pretty_uptime($mystat{'Uptime'})." (".hr_num($mystat{'Questions'}).
" q [".hr_num($qps)." qps], ".hr_num($mystat{'Connections'})." conn,".
" TX: ".hr_num($mystat{'Bytes_sent'}).", RX: ".hr_num($mystat{'Bytes_received'}).")\n";
infoprint "Reads / Writes: ".$mycalc{'pct_reads'}."% / ".$mycalc{'pct_writes'}."%\n";

# Memory usage
infoprint "Total buffers: ".hr_bytes($mycalc{'server_buffers'})." global + ".hr_bytes($mycalc{'per_thread_buffers'})." per thread ($myvar{'max_connections'} max threads)\n";
if ($mycalc{'total_possible_used_memory'} > 2*1024*1024*1024 && $arch eq 32) {
badprint "Allocating > 2GB RAM on 32-bit systems can cause system instability\n";
badprint "Maximum possible memory usage: ".hr_bytes($mycalc{'total_possible_used_memory'})." ($mycalc{'pct_physical_memory'}% of installed RAM)\n";
} elsif ($mycalc{'pct_physical_memory'} > 85) {
badprint "Maximum possible memory usage: ".hr_bytes($mycalc{'total_possible_used_memory'})." ($mycalc{'pct_physical_memory'}% of installed RAM)\n";
push(@generalrec,"Reduce your overall MySQL memory footprint for system stability");
} else {
goodprint "Maximum possible memory usage: ".hr_bytes($mycalc{'total_possible_used_memory'})." ($mycalc{'pct_physical_memory'}% of installed RAM)\n";
}

# Slow queries
if ($mycalc{'pct_slow_queries'} > 5) {
badprint "Slow queries: $mycalc{'pct_slow_queries'}% (".hr_num($mystat{'Slow_queries'})."/".hr_num($mystat{'Questions'}).")\n";
} else {
goodprint "Slow queries: $mycalc{'pct_slow_queries'}% (".hr_num($mystat{'Slow_queries'})."/".hr_num($mystat{'Questions'}).")\n";
}
if ($myvar{'long_query_time'} > 10) { push(@adjvars,"long_query_time (<= 10)"); }
if (defined($myvar{'log_slow_queries'})) {
if ($myvar{'log_slow_queries'} eq "OFF") { push(@generalrec,"Enable the slow query log to troubleshoot bad queries"); }
}

# Connections
if ($mycalc{'pct_connections_used'} > 85) {
badprint "Highest connection usage: $mycalc{'pct_connections_used'}% ($mystat{'Max_used_connections'}/$myvar{'max_connections'})\n";
push(@adjvars,"max_connections (> ".$myvar{'max_connections'}.")");
push(@adjvars,"wait_timeout (< ".$myvar{'wait_timeout'}.")","interactive_timeout (< ".$myvar{'interactive_timeout'}.")");
push(@generalrec,"Reduce or eliminate persistent connections to reduce connection usage")
} else {
goodprint "Highest usage of available connections: $mycalc{'pct_connections_used'}% ($mystat{'Max_used_connections'}/$myvar{'max_connections'})\n";
}

# Key buffer
if (!defined($mycalc{'total_myisam_indexes'}) and $doremote == 1) {
push(@generalrec,"Unable to calculate MyISAM indexes on remote MySQL server < 5.0.0");
} elsif ($mycalc{'total_myisam_indexes'} =~ /^fail$/) {
badprint "Cannot calculate MyISAM index size – re-run script as root user\n";
} elsif ($mycalc{'total_myisam_indexes'} == "0") {
badprint "None of your MyISAM tables are indexed – add indexes immediately\n";
} else {
if ($myvar{'key_buffer_size'} < $mycalc{'total_myisam_indexes'} && $mycalc{'pct_keys_from_mem'} < 95) {
badprint "Key buffer size / total MyISAM indexes: ".hr_bytes($myvar{'key_buffer_size'})."/".hr_bytes($mycalc{'total_myisam_indexes'})."\n";
push(@adjvars,"key_buffer_size (> ".hr_bytes($mycalc{'total_myisam_indexes'}).")");
} else {
goodprint "Key buffer size / total MyISAM indexes: ".hr_bytes($myvar{'key_buffer_size'})."/".hr_bytes($mycalc{'total_myisam_indexes'})."\n";
}
if ($mystat{'Key_read_requests'} > 0) {
if ($mycalc{'pct_keys_from_mem'} < 95) {
badprint "Key buffer hit rate: $mycalc{'pct_keys_from_mem'}% (".hr_num($mystat{'Key_read_requests'})." cached / ".hr_num($mystat{'Key_reads'})." reads)\n";
} else {
goodprint "Key buffer hit rate: $mycalc{'pct_keys_from_mem'}% (".hr_num($mystat{'Key_read_requests'})." cached / ".hr_num($mystat{'Key_reads'})." reads)\n";
}
} else {
# No queries have run that would use keys
}
}

# Query cache
if (!mysql_version_ge(4)) {
# MySQL versions < 4.01 don't support query caching
push(@generalrec,"Upgrade MySQL to version 4+ to utilize query caching");
} elsif ($myvar{'query_cache_size'} < 1) {
badprint "Query cache is disabled\n";
push(@adjvars,"query_cache_size (>= 8M)");
} elsif ($mystat{'Com_select'} == 0) {
badprint "Query cache cannot be analyzed – no SELECT statements executed\n";
} else {
if ($mycalc{'query_cache_efficiency'} < 20) {
badprint "Query cache efficiency: $mycalc{'query_cache_efficiency'}% (".hr_num($mystat{'Qcache_hits'})." cached / ".hr_num($mystat{'Qcache_hits'}+$mystat{'Com_select'})." selects)\n";
push(@adjvars,"query_cache_limit (> ".hr_bytes_rnd($myvar{'query_cache_limit'}).", or use smaller result sets)");
} else {
goodprint "Query cache efficiency: $mycalc{'query_cache_efficiency'}% (".hr_num($mystat{'Qcache_hits'})." cached / ".hr_num($mystat{'Qcache_hits'}+$mystat{'Com_select'})." selects)\n";
}
if ($mycalc{'query_cache_prunes_per_day'} > 98) {
badprint "Query cache prunes per day: $mycalc{'query_cache_prunes_per_day'}\n";
if ($myvar{'query_cache_size'} > 128*1024*1024) {
push(@generalrec,"Increasing the query_cache size over 128M may reduce performance");
push(@adjvars,"query_cache_size (> ".hr_bytes_rnd($myvar{'query_cache_size'}).") [see warning above]");
} else {
push(@adjvars,"query_cache_size (> ".hr_bytes_rnd($myvar{'query_cache_size'}).")");
}
} else {
goodprint "Query cache prunes per day: $mycalc{'query_cache_prunes_per_day'}\n";
}
}

# Sorting
if ($mycalc{'total_sorts'} == 0) {
# For the sake of space, we will be quiet here
# No sorts have run yet
} elsif ($mycalc{'pct_temp_sort_table'} > 10) {
badprint "Sorts requiring temporary tables: $mycalc{'pct_temp_sort_table'}% (".hr_num($mystat{'Sort_merge_passes'})." temp sorts / ".hr_num($mycalc{'total_sorts'})." sorts)\n";
push(@adjvars,"sort_buffer_size (> ".hr_bytes_rnd($myvar{'sort_buffer_size'}).")");
push(@adjvars,"read_rnd_buffer_size (> ".hr_bytes_rnd($myvar{'read_rnd_buffer_size'}).")");
} else {
goodprint "Sorts requiring temporary tables: $mycalc{'pct_temp_sort_table'}% (".hr_num($mystat{'Sort_merge_passes'})." temp sorts / ".hr_num($mycalc{'total_sorts'})." sorts)\n";
}

# Joins
if ($mycalc{'joins_without_indexes_per_day'} > 250) {
badprint "Joins performed without indexes: $mycalc{'joins_without_indexes'}\n";
push(@adjvars,"join_buffer_size (> ".hr_bytes($myvar{'join_buffer_size'}).", or always use indexes with joins)");
push(@generalrec,"Adjust your join queries to always utilize indexes");
} else {
# For the sake of space, we will be quiet here
# No joins have run without indexes
}

# Temporary tables
if ($mystat{'Created_tmp_tables'} > 0) {
if ($mycalc{'pct_temp_disk'} > 25 && $mycalc{'max_tmp_table_size'} < 256*1024*1024) {
badprint "Temporary tables created on disk: $mycalc{'pct_temp_disk'}% (".hr_num($mystat{'Created_tmp_disk_tables'})." on disk / ".hr_num($mystat{'Created_tmp_disk_tables'} + $mystat{'Created_tmp_tables'})." total)\n";
push(@adjvars,"tmp_table_size (> ".hr_bytes_rnd($myvar{'tmp_table_size'}).")");
push(@adjvars,"max_heap_table_size (> ".hr_bytes_rnd($myvar{'max_heap_table_size'}).")");
push(@generalrec,"When making adjustments, make tmp_table_size/max_heap_table_size equal");
push(@generalrec,"Reduce your SELECT DISTINCT queries without LIMIT clauses");
} elsif ($mycalc{'pct_temp_disk'} > 25 && $mycalc{'max_tmp_table_size'} >= 256) {
badprint "Temporary tables created on disk: $mycalc{'pct_temp_disk'}% (".hr_num($mystat{'Created_tmp_disk_tables'})." on disk / ".hr_num($mystat{'Created_tmp_disk_tables'} + $mystat{'Created_tmp_tables'})." total)\n";
push(@generalrec,"Temporary table size is already large – reduce result set size");
push(@generalrec,"Reduce your SELECT DISTINCT queries without LIMIT clauses");
} else {
goodprint "Temporary tables created on disk: $mycalc{'pct_temp_disk'}% (".hr_num($mystat{'Created_tmp_disk_tables'})." on disk / ".hr_num($mystat{'Created_tmp_disk_tables'} + $mystat{'Created_tmp_tables'})." total)\n";
}
} else {
# For the sake of space, we will be quiet here
# No temporary tables have been created
}

# Thread cache
if ($myvar{'thread_cache_size'} eq 0) {
badprint "Thread cache is disabled\n";
push(@generalrec,"Set thread_cache_size to 4 as a starting value");
push(@adjvars,"thread_cache_size (start at 4)");
} else {
if ($mycalc{'thread_cache_hit_rate'} <= 50) {
badprint "Thread cache hit rate: $mycalc{'thread_cache_hit_rate'}% (".hr_num($mystat{'Threads_created'})." created / ".hr_num($mystat{'Connections'})." connections)\n";
push(@adjvars,"thread_cache_size (> $myvar{'thread_cache_size'})");
} else {
goodprint "Thread cache hit rate: $mycalc{'thread_cache_hit_rate'}% (".hr_num($mystat{'Threads_created'})." created / ".hr_num($mystat{'Connections'})." connections)\n";
}
}

# Table cache
if ($mystat{'Open_tables'} > 0) {
if ($mycalc{'table_cache_hit_rate'} < 20) {
badprint "Table cache hit rate: $mycalc{'table_cache_hit_rate'}% (".hr_num($mystat{'Open_tables'})." open / ".hr_num($mystat{'Opened_tables'})." opened)\n";
if (mysql_version_ge(5, 1)) {
push(@adjvars,"table_cache (> ".$myvar{'table_open_cache'}.")");
} else {
push(@adjvars,"table_cache (> ".$myvar{'table_cache'}.")");
}
push(@generalrec,"Increase table_cache gradually to avoid file descriptor limits");
} else {
goodprint "Table cache hit rate: $mycalc{'table_cache_hit_rate'}% (".hr_num($mystat{'Open_tables'})." open / ".hr_num($mystat{'Opened_tables'})." opened)\n";
}
}

# Open files
if (defined $mycalc{'pct_files_open'}) {
if ($mycalc{'pct_files_open'} > 85) {
badprint "Open file limit used: $mycalc{'pct_files_open'}% (".hr_num($mystat{'Open_files'})."/".hr_num($myvar{'open_files_limit'}).")\n";
push(@adjvars,"open_files_limit (> ".$myvar{'open_files_limit'}.")");
} else {
goodprint "Open file limit used: $mycalc{'pct_files_open'}% (".hr_num($mystat{'Open_files'})."/".hr_num($myvar{'open_files_limit'}).")\n";
}
}

# Table locks
if (defined $mycalc{'pct_table_locks_immediate'}) {
if ($mycalc{'pct_table_locks_immediate'} < 95) {
badprint "Table locks acquired immediately: $mycalc{'pct_table_locks_immediate'}%\n";
push(@generalrec,"Optimize queries and/or use InnoDB to reduce lock wait");
} else {
goodprint "Table locks acquired immediately: $mycalc{'pct_table_locks_immediate'}% (".hr_num($mystat{'Table_locks_immediate'})." immediate / ".hr_num($mystat{'Table_locks_waited'}+$mystat{'Table_locks_immediate'})." locks)\n";
}
}

# Performance options
if (!mysql_version_ge(4, 1)) {
push(@generalrec,"Upgrade to MySQL 4.1+ to use concurrent MyISAM inserts");
} elsif ($myvar{'concurrent_insert'} eq "OFF") {
push(@generalrec,"Enable concurrent_insert by setting it to 'ON'");
} elsif ($myvar{'concurrent_insert'} eq 0) {
push(@generalrec,"Enable concurrent_insert by setting it to 1");
}
if ($mycalc{'pct_aborted_connections'} > 5) {
badprint "Connections aborted: ".$mycalc{'pct_aborted_connections'}."%\n";
push(@generalrec,"Your applications are not closing MySQL connections properly");
}

# InnoDB
if (defined $myvar{'have_innodb'} && $myvar{'have_innodb'} eq "YES" && defined $enginestats{'InnoDB'}) {
if ($myvar{'innodb_buffer_pool_size'} > $enginestats{'InnoDB'}) {
goodprint "InnoDB data size / buffer pool: ".hr_bytes($enginestats{'InnoDB'})."/".hr_bytes($myvar{'innodb_buffer_pool_size'})."\n";
} else {
badprint "InnoDB data size / buffer pool: ".hr_bytes($enginestats{'InnoDB'})."/".hr_bytes($myvar{'innodb_buffer_pool_size'})."\n";
push(@adjvars,"innodb_buffer_pool_size (>= ".hr_bytes_rnd($enginestats{'InnoDB'}).")");
}
}
}

# Take the two recommendation arrays and display them at the end of the output
sub make_recommendations {
print "\n——– Recommendations —————————————————–\n";
if (@generalrec > 0) {
print "General recommendations:\n";
foreach (@generalrec) { print " ".$_."\n"; }
}
if (@adjvars > 0) {
print "Variables to adjust:\n";
if ($mycalc{'pct_physical_memory'} > 90) {
print " *** MySQL's maximum memory usage is dangerously high ***\n".
" *** Add RAM before increasing MySQL buffer variables ***\n";
}
foreach (@adjvars) { print " ".$_."\n"; }
}
if (@generalrec == 0 && @adjvars ==0) {
print "No additional performance recommendations are available.\n"
}
print "\n";
}

# —————————————————————————
# BEGIN 'MAIN'
# —————————————————————————
print "\n >> MySQLTuner $tunerversion – Major Hayden <major\@mhtx.net>\n".
" >> Bug reports, feature requests, and downloads at http://mysqltuner.com/\n".
" >> Run with '–help' for additional options and output filtering\n";
mysql_setup; # Gotta login first
os_setup; # Set up some OS variables
get_all_vars; # Toss variables/status into hashes
validate_tuner_version; # Check current MySQLTuner version
validate_mysql_version; # Check current MySQL version
check_architecture; # Suggest 64-bit upgrade
check_storage_engines; # Show enabled storage engines
security_recommendations; # Display some security recommendations
calculations; # Calculate everything we need
mysql_stats; # Print the server stats
make_recommendations; # Make recommendations based on stats
# —————————————————————————
# END 'MAIN'
# —————————————————————————

# Local variables:
# indent-tabs-mode: t
# cperl-indent-level: 8
# perl-indent-level: 8
# End:

To run the script, simply make it executable and run it:

chmod +x mysqltuner.pl
# ./mysqltuner.pl

You may have to provide your administrative username and password.

The output will look something similar below-

You need to check mainly recommendations section at the end. It shows which variables you should adjust in the section of your my.cnf (on debian file located at /etc/mysql/my.cnf).

Src: 

https://raw.github.com/rackerhacker/MySQLTuner-perl/master/mysqltuner.pl

http://www.debianadmin.com/check-your-mysql-server-performance-with-mysqltuner.html

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