Wordpress - Editing wp-config.php

As part of the WordPress installation, you must modify the wp-config.php file to define the WordPress configuration settings required to access your MySQL database.
This file, wp-config.php, does not exist in a downloaded copy of WordPress; you need to create it. The wp-config-sample.php file is provided as an example to work from. Advanced settings and examples are provided below.
To change the wp-config.php file for your installation, you will need this information:

Database Name 
Database Name used by WordPress
Database Username 
Username used to access Database
Database Password 
Password used by Username to access Database
Database Host 
The hostname of your Database Server
If your hosting provider installed WordPress for you, get the information from them. If you manage your own web server or hosting account, you will have this information as a result of creating the database and user.


Configure Database Settings

Important: never use a word processor like Microsoft Word for editing WordPress files!
Locate the file wp-config-sample.php in the base directory of your WordPress directory and open in a text editor.

NOTE: Since Version 2.6, wp-config.php can be moved to the directory directly above the WordPress application directory.


Default wp-config-sample.php

This is an example of a default wp-config-sample.php. The values here are examples to show you what to do. You need to make changes on your own web site not here. If you make changes here by using the edit button, they will not work and you will be showing your password details to the world.

// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define('DB_NAME', 'putyourdbnamehere');
/** MySQL database username */
define('DB_USER', 'usernamehere');
/** MySQL database password */
define('DB_PASSWORD', 'yourpasswordhere');
/** MySQL hostname */
define('DB_HOST', 'localhost');
NOTE: Text inside /* */ are comments, for information purposes only.
NOTE: Do not change these details here by editing this page, change them on your web server.


Set Database Name

Replace putyourdbnamehere, with the name of your database, e.g. MyDatabaseName. 
define('DB_NAME', 'MyDatabaseName'); // Example MySQL database name

Set Database User

Replace usernamehere, with the name of your username e.g. MyUserName. 
define('DB_USER', 'MyUserName'); // Example MySQL username

Set Database Password

Replace yourpasswordhere, with the your password, e.g. MyPassWord. 
define('DB_PASSWORD', 'MyPassWord'); // Example MySQL password

Set Database Host

Replace localhost, with the name of your database host, e.g. MyDatabaseHost. 
define('DB_HOST', 'MyDatabaseHost'); // Example MySQL Database host


NOTE: There is a good chance you will NOT have to change it. If you are unsure, try installing with the default value of 'localhost' and see if it works. If the install fails, contact your web hosting provider.

Possible DB_HOST values

Different hosting companies use different network settings for their mysql database's. If your hosting company is listed below in the left column, the value on the right is similar to the correct value for DB_HOST. Contact your tech support and/or search your hosting companies online Documentation to be sure.
Hosting Company DB_HOST Value Guess
1and1 db12345678
AN Hosting localhost
A Small Orange localhost
BlueHost localhost
DreamHost mysql.example.com
GoDaddy Go to MySQL and edit the database to find the server name.
HostGator localhost
HostICan localhost
ICDSoft localhost:/tmp/mysql5.sock
IPower username.ipowermysql.com
LaughingSquid localhost
MediaTemple GridServer internal-db.s44441.gridserver.com
NearlyFreeSpeech.Net username.db
one.com localhost
pair Networks dbnnnx.pair.com
Rackspace Cloud mysql50-01.wc1.dfw1.stabletransit.com
Yahoo mysql
Hosts with cPanel localhost
Hosts with Plesk localhost
Hosts with DirectAdmin localhost
Tophost.it sql.your-domain-name.it



MySQL Alternate Port

If your host uses an alternate port number for your database you'll need to change the DB_HOST value in the wp-config.php file to reflect the alternate port provided by your host.
For localhost 
define('DB_HOST', 'localhost:3307');
Other 
define('DB_HOST', 'mysql.example.com:3307');
Replace 3307 with whatever port number you host gives you.

Database character set

As of WordPress Version 2.2, DB_CHARSET was made available to allow designation of the database character set (e.g. tis620 for TIS620 Thai) to be used when defining the MySQL database tables.
The default value of utf8 (Unicode UTF-8) is almost always the best option. UTF-8 supports any language, so you typically want to leave DB_CHARSET at utf8 and use the DB_COLLATE value for your language instead.
This example shows utf8 which is considered the WordPress default value: 
define('DB_CHARSET', 'utf8');
WARNING: Those performing new installations
There usuallly should be no reason to change the default value of DB_CHARSET. If your blog needs a different character set, please read Character Sets and Collations MySQL Supports for valid DB_CHARSET values.
WARNING: Those performing upgrades (especially blogs that existed before 2.2)
If DB_CHARSET and DB_COLLATE do not exist in your wp-config.php file, DO NOT add either definition to your wp-config.php file unless you read and understand Converting Database Character Sets. Adding DB_CHARSET and DB_COLLATE to the wp-config.php file, for an existing blog, can cause major problems.

Database collation

As of WordPress Version 2.2, DB_COLLATE was made available to allow designation of the database collation (i.e. the sort order of the character set). In most cases, this value should be left blank (null) so the database collation will be automatically assigned by MySQL based on the database character set specified by DB_CHARSET. Set DB_COLLATE to one of the UTF-8 values defined in UTF-8 character sets for most Western European languages.
The WordPress default DB_COLLATE value: 
define('DB_COLLATE', );
UTF-8 Unicode General collation 
define('DB_COLLATE', 'utf8_general_ci');
UTF-8 Unicode Turkish collation 
define('DB_COLLATE', 'utf8_turkish_ci');
WARNING: Those performing new installations
There usually should be no reason to change the default value of DB_COLLATE. Leaving the value blank (null) will insure the collation is automatically assigned by MySQL when the database tables are created.
WARNING: Those performing upgrades (especially blogs that existed before 2.2)
If DB_COLLATE and DB_CHARSET do not exist in your wp-config.php file, DO NOT add either definition to your wp-config.php file unless you read and understand Converting Database Character Sets. And you may be in need of a WordPress upgrade.


Security Keys

In Version 2.6, three (3) security keys, AUTH_KEY, SECURE_AUTH_KEY, and LOGGED_IN_KEY, were added to ensure better encryption of information stored in the user's cookies. (These collectively replaced a single key introduced in Version 2.5.) In Version 2.7 a fourth key, NONCE_KEY, was added to this group. When each key was added, corresponding salts were added: AUTH_SALT, SECURE_AUTH_SALT, LOGGED_IN_SALT, and NONCE_SALT.
You don't have to remember the keys, just make them long, random and complicated -- or better yet, use the the online generator. You can change these at any point in time to invalidate all existing cookies. This does mean that all users will have to login again.
Example (don't use these!): 
define('AUTH_KEY',         't`DK%X:>xy|e-Z(BXb/f(Ur`8#~UzUQG-^_Cs_GHs5U-&Wb?pgn^p8(2@}IcnCa|');
define('SECURE_AUTH_KEY',  'D&ovlU#|CvJ##uNq}bel+^MFtT&.b9{UvR]g%ixsXhGlRJ7q!h}XWdEC[BOKXssj');
define('LOGGED_IN_KEY',    'MGKi8Br(&{H*~&0s;{k0(hdXW|0M=X={we6;Mpvtg+V.o<$|#_}qG(GaVDEsn,~*4i');
define('NONCE_SALT',       'a|#h{c5|P &xWs4IZ20c2&%4!c(/uG}W:mAvy
A secret key makes your site harder to hack and access harder to crack by adding random elements to the password.

In simple terms, a secret key is a password with elements that 
make it harder to generate enough options to break through your security
 barriers. A password like "password" or "test" is simple and easily 
broken. A random, unpredictable password such as 
"88a7da62429ba6ad3cb3c76a09641fc" takes years to come up with the right 
combination. A 'salt is used to further enhance the security of the generated result.

The four keys are required for the enhanced security. The four 
salts are recommended, but are not required, because WordPress will 
generate salts for you if none are provided. They are included in 
wp-config.php by default for inclusiveness.

For more information on the technical background and breakdown of secret keys and secure passwords, see:


  Advanced Options 
The following sections may contain advanced / unsupported information, so please make sure you practice regular backups and know how to restore them before experimenting on a production installation.


  table_prefix 
The $table_prefix is the value placed in the front of your database tables.  Change the value if you want to use something other than wp_ for your database prefix.  Typically this is changed if you are installing multiple WordPress blogs in the same database.


// You can have multiple installations in one database if you give each a unique prefix
$table_prefix  = 'r235_';   // Only numbers, letters, and underscores please!

A second blog installation using the same database can be achieved 
simply by using a different prefix than your other installations.


$table_prefix  = 'y77_';   // Only numbers, letters, and underscores please!

  WordPress address (URL) 
WP_SITEURL, defined since WordPress Version 2.2,
 allows the WordPress address (URL) to be defined.  The value defined is
 the address where your WordPress core files reside.  It should include 
the http:// part too.  Do not put a slash "/" at the end.  Setting this value in wp-config.php overrides the wp_options table value for siteurl and disables the WordPress address (URL) field in the Administration > Settings > General panel. 


NOTE:
 It won't change the Database value though, and the url will revert to 
the old database value if this line is removed from wp-config. Use the RELOCATE constant to change the siteurl value in the database.
If WordPress is installed into a directory called "wordpress" for the domain example.com, define WP_SITEURL like this:


define('WP_SITEURL', 'http://example.com/wordpress');

Dynamically set WP_SITEURL based on $_SERVER['HTTP_HOST']


define('WP_SITEURL', 'http://' . $_SERVER['HTTP_HOST'] . '/path/to/wordpressp');

NOTE:
 A safer alternative for some installations would be to use the 
server-generated SERVER_NAME instead of the php/user-generated HTTP_HOST
 which is created dynamically by php based on the value of the HTTP HOST
 Header in the request, thus possibly allowing for file inclusion 
vulnerabilities.  SERVER_NAME is set by the server configuration and is 
static.
Dynamically set WP_SITEURL based on $_SERVER['SERVER_NAME']


define('WP_SITEURL', 'http://' . $_SERVER['SERVER_NAME'] . '/path/to/wordpressp');

 Blog address (URL)
WP_HOME is another wp-config.php option added in WordPress Version 2.2. Similar to WP_SITEURL, WP_HOME overrides the wp_options table value for home but does not change it permanently. home
 is the address you want people to type in their browser to reach your 
WordPress blog. It should include the http:// part and should not have a
 slash "/" at the end. 


define('WP_HOME', 'http://example.com/wordpress'); 

If you are using the technique described in Giving WordPress Its Own Directory then follow the example below.  Remember, you will also be placing an index.php in your web-root directory if you use a setting like this.


define('WP_HOME', 'http://example.com');

Dynamically set WP_HOME based on $_SERVER['HTTP_HOST']


define('WP_HOME',    'http://' . $_SERVER['HTTP_HOST'] . '/path/to/wordpress');

  Moving wp-content 
Since Version 2.6, you can move the wp-content directory, which holds your themes, plugins, and uploads, outside of the WordPress application directory.

Set WP_CONTENT_DIR to the full local path of this directory (no trailing slash), e.g.


define( 'WP_CONTENT_DIR', $_SERVER['DOCUMENT_ROOT'] . '/blog/wp-content' );

Set WP_CONTENT_URL to the full URI of this directory (no trailing slash), e.g.


define( 'WP_CONTENT_URL', 'http://example/blog/wp-content');

Optional

Set WP_PLUGIN_DIR to the full local path of this directory (no trailing slash), e.g.


define( 'WP_PLUGIN_DIR', $_SERVER['DOCUMENT_ROOT'] . '/blog/wp-content/plugins' );

Set WP_PLUGIN_URL to the full URI of this directory (no trailing slash), e.g.


define( 'WP_PLUGIN_URL', 'http://example/blog/wp-content/plugins');

If you have compability issues with plugins
Set PLUGINDIR to the full local path of this directory (no trailing slash), e.g.


define( 'PLUGINDIR', $_SERVER['DOCUMENT_ROOT'] . '/blog/wp-content/plugins' );

 Modify AutoSave Interval
When editing a post, WordPress uses Ajax to auto-save revisions to 
the post as you edit.  You may want to increase this setting for longer 
delays in between auto-saves, or decrease the setting to make sure you 
never lose changes.  The default is 60 seconds.


define('AUTOSAVE_INTERVAL', 160 );  // seconds

 Post Revisions
WordPress, by default, will save copies of each edit made to a post 
or page, allowing the possibility of reverting to a previous version of 
that post or page.  The saving of revisions can be disabled, or a 
maximum number of revisions per post or page can be specified.


 Disable Post Revisions
If you do not set this value, WordPress defaults WP_POST_REVISIONS to true (enable post revisions). If you want to disable the awesome revisions feature, use this setting:


define('WP_POST_REVISIONS', false );

 Specify the Number of Post Revisions
If you want to specify a maximum number of revisions, change false to an integer/number (e.g., 3 or 5).


define('WP_POST_REVISIONS', 3);

 Set Cookie Domain
The domain set in the cookies for WordPress can be specified for those with unusual domain setups.  One reason is if subdomains are used to serve static content.
 To prevent WordPress cookies from being sent with each request to 
static content on your subdomain you can set the cookie domain to your 
non-static domain only.


define('COOKIE_DOMAIN', 'www.askapache.com');

  Enable Multisite / Network Ability 
WP_ALLOW_MULTISITE is a feature introduced in WordPress Version 3.0 to enable multisite functionality previously achieved through WordPress MU. If this setting is absent from wp-config.php it defaults to false.


define('WP_ALLOW_MULTISITE', true);

  Debug 
The WP_DEBUG option, added in WordPress Version 2.3.1, controls the display of some errors and warnings. If this setting is absent from wp-config.php, then the value is assumed to be false. 


NOTE: The true and false values in the example are not set in apostrophes (') because they are boolean values.
define('WP_DEBUG', true);
define('WP_DEBUG', false);

Additionally, if you are planning on modifying some of WordPress' built-in JavaScript, you should enable the following option:


define('SCRIPT_DEBUG', true);

This will allow you to edit the scriptname.dev.js files in the wp-includes/js and wp-admin/js directories.

In WordPress versions since 2.3.2, database errors are printed only if WP_DEBUG is set to true.
 In earlier versions, database errors were always printed. (Database 
errors are handled by the wpdb class and are not affected by PHP's error settings.)

In WordPress version 2.5, setting WP_DEBUG to true also raises the error reporting level
 to E_ALL and activates warnings when deprecated functions or files are 
used; otherwise, WordPress sets the error reporting level to E_ALL ^ E_NOTICE ^ E_USER_NOTICE.


  Disable Javascript Concatenation 
To result in a faster administration area, all Javascript files are concatenated into one URL. If Javascript is failing to work in your administration area, you can try disabling this feature:


define('CONCATENATE_SCRIPTS', false);

  Configure Error Log 
Because wp-config.php is loaded for every page view not 
loaded from a cache file, it is an excellent location to set php ini 
settings that control your php installation.  This is useful if you 
don't have access to a php.ini file, or if you just want to change some 
settings on the fly.

Here is an example that turns php error_logging on and logs them to a specific file.  If WP_DEBUG is defined to true, the errors will also be saved to this file.  Just place this above any require_once or include commands.


@ini_set('log_errors','On');
@ini_set('display_errors','Off');
@ini_set('error_log','/home/example.com/logs/php_error.log');
/* That's all, stop editing! Happy blogging. */

Another example of logging errors, as suggested by Mike Little on the wp-hackers email list:


/**
 * This will log all errors notices and warnings to a file called debug.log in
 * wp-content (if Apache does not have write permission, you may need to create
 * the file first and set the appropriate permissions (i.e. use 666) ) 
 */
define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);
@ini_set('display_errors',0);

A recent suggestion from Mike Little on the Manchester WordPress User Group:


/**
 * This will log all errors notices and warnings to a file called debug.log in
 * wp-content only when WP_DEBUG is true
 */

define('WP_DEBUG', true); // false
if (WP_DEBUG) {
  define('WP_DEBUG_LOG', true);
  define('WP_DEBUG_DISPLAY', false);
  @ini_set('display_errors',0);
}

 Increasing memory allocated to PHP
Also released with Version 2.5, the WP_MEMORY_LIMIT
 option allows you to specify the maximum amount of memory that can be 
consumed by PHP.  This setting may be necessary in the event you receive
 a message such as "Allowed memory size of xxxxxx bytes exhausted".  

This setting increases PHP Memory only for WordPress, not other 
applications.  By default, WordPress will attempt to increase memory 
allocated to PHP to 32MB (code is at beginning of wp-settings.php), so the setting in wp-config.php should reflect something higher than 32MB.

WordPress will automatically check if PHP has been allocated less
 memory than the entered value before utilizing this function.  For 
example, if PHP has been allocated 64MB, there is no need to set this 
value to 64M as WordPress will automatically use all 64MB if need be.

Please note, this setting may not work if your host does not 
allow for increasing the PHP memory limit--in that event, contact your 
host to increase the PHP memory limit. Also, note that many hosts set 
the PHP limit at 8MB.    

Increase PHP Memory to 64MB


define('WP_MEMORY_LIMIT', '64M');

Increase PHP Memory to 96MB


define('WP_MEMORY_LIMIT', '96M');

 Cache
The WP_CACHE setting, if true, includes the wp-content/advanced-cache.php script, when executing wp-settings.php.


define('WP_CACHE', true);

  Custom User and Usermeta Tables 
CUSTOM_USER_TABLE and CUSTOM_USER_META_TABLE are used 
to designated that the user and usermeta tables normally utilized by 
WordPress are not used, instead these values/tables are used to store 
your user information.


define('CUSTOM_USER_TABLE', $table_prefix.'my_users');
define('CUSTOM_USER_META_TABLE', $table_prefix.'my_usermeta');

Please note that permissions in the user_meta tables are stored with 
the table prefix of the site.  So in the CUSTOM_USER_META_TABLE one must
 have entries for each site using that table.
At the very least for the administrator, to avoid the "you do not have 
permissions error" you should have:

prefix1_capabilities = a:1:{s:13:"administrator";b:1;}
and 
prefix2_capabilities = a:1:{s:13:"administrator";b:1;}
etc


  Language and Language Directory 
WPLANG defines the name of the language translation (.mo) file.  WP_LANG_DIR
 defines what directory the WPLANG .mo file resides.  If WP_LANG_DIR is 
not defined WordPress looks first to wp-content/languages and then 
wp-includes/languages for the .mo defined by WPLANG file.


define('WPLANG', 'de_DE');
define('WP_LANG_DIR', $_SERVER['DOCUMENT_ROOT'].'wordpress/languages');

  Save queries for analysis 
The SAVEQUERIES definition saves the database queries to a 
array and that array can be displayed to help analyze those queries.  
The information saves each query, what function called it, and how long 
that query took to execute.  


NOTE: This will have a performance impact on your site, so make sure to turn this off when you aren't debugging.
First, put this in wp-config.php:


define('SAVEQUERIES', true);

Then in the footer of your theme put this:


";
    print_r($wpdb->queries);
    echo "
";
}
?>

Override of default file permissions

The FS_CHMOD_DIR and FS_CHMOD_FILE define statements allow override of default file permissions. These two variables were developed in response to the problem of the core update function failing with hosts (e.g. some Italian hosts) running under suexec. If a host uses restrictive file permissions (e.g. 400) for all user files, and refuses to access files which have group or world permissions set, these definitions could solve the problem. Note that the '0755' is an octal value and is not delineated with single quotes ('). See Also: Changing File Permissions 
define('FS_CHMOD_DIR', (0755 & ~ umask()));
define('FS_CHMOD_FILE', (0644 & ~ umask()));

WordPress Upgrade Constants

You should define as few of the below constants needed to correct your update issues.
The most common causes of needing to define these are:
  • Host running with a special installation setup involving Symlinks, You may need to define the path-related constants (FTP_BASE, FTP_CONTENT_DIR, and FTP_PLUGIN_DIR), Often defining simply the base will be enough.
  • Certain PHP installations shiped with a PHP FTP Extension which is incompatible with certain FTP Servers, under these rare situations, you may need to define FTP_METHOD to 'ftpsockets'
The following are valid constants for WordPress updates:
  • FS_METHOD forces the filesystem method. It should only be "direct", "ssh", "ftpext", or "ftpsockets". Generally, You should only change this if you are experiencing update problems, If you change it, and it doesnt help change it back/remove it, Under most circumstances, setting it to 'ftpsockets' will work if the automatically chosen method does not.
    • (Primary Preference) "direct" forces it to use Direct File I/O requests from within PHP, this is fraught with opening up security issues on poorly configured hosts, This is chosen automatically when appropriate.
    • (Secondary Preference) "ssh2" is to force the usage of the SSH PHP Extension if installed
    • (3rd Preference) "ftpext" is to force the usage of the FTP PHP Extension for FTP Access, and finally
    • (4th Preference) "ftpsockets" utilises the PHP Sockets Class for FTP Access.
  • FTP_BASE is the full path to the "base"(ABSPATH) folder of the WordPress installation.
  • FTP_CONTENT_DIR is the full path to the wp-content folder of the WordPress installation.
  • FTP_PLUGIN_DIR is the full path to the plugins folder of the WordPress installation.
  • FTP_PUBKEY is the full path to your SSH public key.
  • FTP_PRIKEY is the full path to your SSH private key.
  • FTP_USER is either user FTP or SSH username. Most likely these are the same, but use the appropriate one for the type of update you wish to do.
  • FTP_PASS is the password for the username entered for FTP_USER. If you are using SSH public key authentication this can be omitted.
  • FTP_HOST is the hostname:port combination for your SSH/FTP server. The default FTP port is 21 and the default SSH port is 22, These do not need to be mentioned.
  • FTP_SSL TRUE for SSL-connection if supported by the underlying transport, Not available on all servers. This is for "Secure FTP" not for SSH SFTP. 
define('FS_METHOD', 'ftpext');
define('FTP_BASE', '/path/to/wordpress/');
define('FTP_CONTENT_DIR', '/path/to/wordpress/wp-content/');
define('FTP_PLUGIN_DIR ', '/path/to/wordpress/wp-content/plugins/');
define('FTP_PUBKEY', '/home/username/.ssh/id_rsa.pub');
define('FTP_PRIKEY', '/home/username/.ssh/id_rsa');
define('FTP_USER', 'username');
define('FTP_PASS', 'password');
define('FTP_HOST', 'ftp.example.org');
define('FTP_SSL', false);

Enabling SSH Upgrade Access

To enable SSH2 as an upgrade option you will need to install the pecl SSH2 extension. To install this library you will need to issue a command similar to the following or talk to your web hosting provider to get this installed: 
pecl install ssh2
After installing the pecl ssh2 extension you will need to modify your php configuration to automatically load this extension.
pecl is provided by the pear package in most linux distributions. To install pecl in Redhat/Fedora/CentOS: 
yum -y install php-pear
To install pecl in Debian/Ubuntu: 
apt-get install php-pear
It is recommended to use a private key that is not pass-phrase protected. There have been numerous reports that pass phrase protected private keys do not work properly. If you decide to try a pass phrase protected private key you will need to enter the pass phrase for the private key as FTP_PASS, or entering it in the "Password" field in the presented credential field when installing updates.
If you're still not clear on how to use SSH for upgrading or installing WordPress/plugins, read through this tutorial.

Alternative Cron

Use this, for example, if scheduled posts are not getting published. According to Otto's forum explanation, "this alternate method uses a redirection approach, which makes the users browser get a redirect when the cron needs to run, so that they come back to the site immediately while cron continues to run in the connection they just dropped. This method is a bit iffy sometimes, which is why it's not the default." 
define('ALTERNATE_WP_CRON', true);

Additional Defined Constants

Here are additional constants that can be defined, but probably shouldn't be. The Cookie definitions are particularly useful if you have an unusual domain setup. 
define('COOKIEPATH', preg_replace('|https?://[^/]+|i', '', get_option('home') . '/' ) );
define('SITECOOKIEPATH', preg_replace('|https?://[^/]+|i', '', get_option('siteurl') . '/' ) );
define('ADMIN_COOKIE_PATH', SITECOOKIEPATH . 'wp-admin' );
define('PLUGINS_COOKIE_PATH', preg_replace('|https?://[^/]+|i', '', WP_PLUGIN_URL)  );
define('TEMPLATEPATH', get_template_directory());
define('STYLESHEETPATH', get_stylesheet_directory());
define('DISABLE_WP_CRON', true);

Empty Trash

Added with Version 2.9, this constant controls the number of days before WordPress permanently deletes posts, pages, attachments, and comments, from the trash bin. The default is 30 days: 
define('EMPTY_TRASH_DAYS', 30 );  // 30 days
To disable trash set the number of days to zero. Note that WordPress will not ask for confirmation when someone clicks on "Delete Permanently". 
define('EMPTY_TRASH_DAYS', 0 );  // zero days

Automatic Database Optimizing

Added with Version 2.9, there is automatic database optimization support, which you can enable by adding the following define to your wp-config.php file only when the feature is required 
define('WP_ALLOW_REPAIR', true);
The script can be found at {$your_site}/wp-admin/maint/repair.php
Please Note: That this define enables the functionality, The user does not need to be logged in to access this functionality when this define is set. This is because its main intent is to repair a corrupted database, Users can often not login when the database is corrupt.

Do not upgrade global tables

A DO_NOT_UPGRADE_GLOBAL_TABLES define prevents dbDelta() and the upgrade functions from doing expensive queries against global tables.
Sites that have large global tables (particularly users and usermeta), as well as sites that share user tables with bbPress and other WordPress installs, can prevent the upgrade from changing those tables during upgrade by defining DO_NOT_UPGRADE_GLOBAL_TABLES. Since an ALTER, or an unbounded DELETE or UPDATE, can take a long time to complete, large sites usually want to avoid these being run as part of the upgrade so they can handle it themselves. Further, if installations are sharing user tables between multiple bbPress and WordPress installs it maybe necessary to want one site to be the upgrade master. 
define('DO_NOT_UPGRADE_GLOBAL_TABLES', true);

View All Defined Constants

Php has a function that returns an array of all the currently defined constants with their values. 
print_r(@get_defined_constants());

Disable the Plugin and Theme Editor

Occasionally you may wish to disable the plugin or theme editor to prevent overzealous users from being able to edit sensitive files and potentially crash the site. Disabling these also provides an additional layer of security if a hacker gains access to a well-privileged user account. 
define('DISALLOW_FILE_EDIT',true);

Disable Plugin and Theme Update and Installation

This will block users being able to use the plugin and theme installation/update functionality from the WordPress admin area. Setting this constant also disables the Plugin and Theme editor (i.e. you don't need to set DISALLOW_FILE_MODS and DISALLOW_FILE_EDIT, as on it's own DISALLOW_FILE_MODS will have the same effect). 
define('DISALLOW_FILE_MODS',true);

Double Check Before Saving

Be sure to check for leading and/or trailing spaces around any of the above values you entered, and DON'T delete the single quotes!
Before you save the file, be sure to double-check that you have not accidentally deleted any of the single quotes around the parameter values. Be sure there is nothing after the closing PHP tag in the file. The last thing in the file should be ?> and nothing else. No spaces.
To save the file, choose File > Save As > wp-config.php and save the file in the root of your WordPress install. Upload the file to your web server and you're ready to install WordPress!

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