Title: Memcached Object Cache
Author: Mark Jaquith
Published: <strong>2005年12月19日</strong>
Last modified: 2022年11月8日

---

プラグインを検索

このプラグインは **WordPress の最新3回のメジャーリリースに対してテストされていま
せん**。もうメンテナンスやサポートがされていないかもしれず、最新バージョンの WordPress
で使用した場合は互換性の問題が発生する可能性があります。

![](https://s.w.org/plugins/geopattern-icon/memcached.svg)

# Memcached Object Cache

 作者: [Mark Jaquith](https://profiles.wordpress.org/markjaquith/)

[ダウンロード](https://downloads.wordpress.org/plugin/memcached.4.0.0.zip)

 * [詳細](https://ja.wordpress.org/plugins/memcached/#description)
 * [レビュー](https://ja.wordpress.org/plugins/memcached/#reviews)
 *  [インストール](https://ja.wordpress.org/plugins/memcached/#installation)
 * [開発](https://ja.wordpress.org/plugins/memcached/#developers)

 [サポート](https://wordpress.org/support/plugin/memcached/)

## 説明

Memcached Object Cache provides a persistent backend for the WordPress object cache.
A memcached server and the PECL memcache extension are required.

## インストール

 1. Install [memcached](http://danga.com/memcached) on at least one server. Note the
    connection info. The default is `127.0.0.1:11211`.
 2. Install the [PECL memcache extension](http://pecl.php.net/package/memcache)
 3. Copy object-cache.php to wp-content
 4. Add the `WP_CACHE_KEY_SALT` constant to the `wp-config.php`:
 5. `php
     define( 'WP_CACHE_KEY_SALT', '...long random string...' );

This helps prevent cache pollution when multiplte WordPress installs are using the
same Memcached server. The value must be unique for each WordPress install.

## FAQ

### How can I manually specify the memcached server(s)?

Add something similar to the following to wp-config.php above `/* That's all, stop
editing! Happy blogging. */`:

    ```
    $memcached_servers = array(
        'default' => array(
            '10.10.10.20:11211',
            '10.10.10.30:11211'
        )
    );
    ```

The top level array keys, are cache groups, where ‘default’ corresponds to any cache
group that is not explicitly defined. This allows for specifying memcached servers
that only handle certain cache groups. The most common use is only specifying ‘default’.

Possible cache groups are:

    ```
    {$taxonomy}_relationships
    {$meta_type}_meta
    {$taxonomy}_relationships
    blog-details
    blog-id-cache
    blog-lookup
    bookmark
    calendar
    category
    comment
    counts
    general
    global-posts
    options
    plugins
    post_ancestors
    post_meta
    posts
    rss
    site-lookup
    site-options
    site-transient
    terms
    themes
    timeinfo
    transient
    user_meta
    useremail
    userlogins
    usermeta
    users
    userslugs
    widget
    ```

## 評価

![](https://secure.gravatar.com/avatar/9610e77b9c1acfe8436ce0afe252d9536b6b4b4f23aa97a10ebc24cba9bbd76f?
s=60&d=retro&r=g)

### 󠀁[Amazing performance improvement!](https://wordpress.org/support/topic/amazing-performance-improvement/)󠁿

 [rambillo](https://profiles.wordpress.org/rambillo/) 2023年10月21日

Install is not like other plugins — and in fact if you do upload it to plugins and
then activate it, it’ll bring your site down in many cases. You can upload it (but
don’t activate!) and then use the server side to move the plugin file manually into
wp-content (and then delete the uploaded plugin folder and readme.txt). But that’s
not enough to make the whole thing work! You also need memcached running on your
server and properly configured, and the pecl memcache extension compiled on the 
server side in your php configuration, too. Make sure to use a unique salt as well.
Once it’s all there, the speed improvement is significant! Happy to try and help
those that respond to this thread if you need — or at least try to get you pointed
in the right direction. Thanks for the plugin, devs! Appreciate as you update and
keep current as well!

![](https://secure.gravatar.com/avatar/a15ec539baae35aa862ff604b11ba327a6a990d0ff7372d55314217f7099ab5f?
s=60&d=retro&r=g)

### 󠀁[Can t install the plugin](https://wordpress.org/support/topic/can-t-install-the-plugin/)󠁿

 [kalagan80](https://profiles.wordpress.org/kalagan80/) 2023年9月4日

Unable to install the plugin : application not recognized.

![](https://secure.gravatar.com/avatar/fb5ab2d835f31b7bac4b4df4d061d4bf782071e55329e792b2e0ef25c61da290?
s=60&d=retro&r=g)

### 󠀁[Cannot redeclare wp_cache_add](https://wordpress.org/support/topic/cannot-redeclare-wp_cache_add-4/)󠁿

 [terrykernan](https://profiles.wordpress.org/terrykernan/) 2023年5月17日 1 reply

Tip for others here, if you are getting this error: “Cannot redeclare wp_cache_add”
It probably means you have the object-cache.php file in the wrong directory, it 
should not be in the plugins/memcached/ folder, it should be moved to the wp-content
folder!

![](https://secure.gravatar.com/avatar/374ea40afb714496967ecdd047f26a4c48c9b2b6acac65646e08bf27b7ad8806?
s=60&d=retro&r=g)

### 󠀁[FATAL ERROR PHP](https://wordpress.org/support/topic/fatal-error-php-9/)󠁿

 [legarsfred](https://profiles.wordpress.org/legarsfred/) 2023年4月5日 1 reply

Fatal error: Cannot redeclare wp_cache_add() (previously declared in /htdocs/wp-
includes/cache.php:41) in /htdocs/wp-content/plugins/memcached/object-cache.php 
on line 19

![](https://secure.gravatar.com/avatar/93083231f4567aaebde042533a0a3b62f0a7da89cf857125fa58a5c7f71f665d?
s=60&d=retro&r=g)

### 󠀁[Works great!](https://wordpress.org/support/topic/works-great-8687/)󠁿

 [Miguel](https://profiles.wordpress.org/miguelgilmartinez/) 2023年2月16日

It works well even with WPRocket Cache plugin. If you get fatal errors don’t forget
to install PECL memcache module to PHP.

![](https://secure.gravatar.com/avatar/2525672f136bff92260533e5d4658c745e53d7bbab383c1e5ca8f7b744c43638?
s=60&d=retro&r=g)

### 󠀁[Fatal error](https://wordpress.org/support/topic/fatal-error-4358/)󠁿

 [Alex Volkov](https://profiles.wordpress.org/vol4ikman/) 2023年2月3日 2 replies

Fatal error: Cannot redeclare wp_cache_add() (previously declared in /home/accessib/
public_html/wp-includes/cache.php:41) in /public_html/wp-content/plugins/memcached/
object-cache.php on line 19

 [ 30件のレビューをすべて表示 ](https://wordpress.org/support/plugin/memcached/reviews/)

## 貢献者と開発者

Memcached Object Cache はオープンソースソフトウェアです。以下の人々がこのプラグイン
に貢献しています。

貢献者

 *   [ Mark Jaquith ](https://profiles.wordpress.org/markjaquith/)
 *   [ Ryan Boren ](https://profiles.wordpress.org/ryan/)
 *   [ Matt Martz ](https://profiles.wordpress.org/sivel/)
 *   [ Andy Skelton ](https://profiles.wordpress.org/andy/)
 *   [ Andrew Nacin ](https://profiles.wordpress.org/nacin/)
 *   [ Barry ](https://profiles.wordpress.org/barry/)
 *   [ Erick Hitter ](https://profiles.wordpress.org/ethitter/)
 *   [ nickdaugherty ](https://profiles.wordpress.org/nickdaugherty/)
 *   [ Mohammad Jangda ](https://profiles.wordpress.org/batmoo/)
 *   [ Simon Wheatley ](https://profiles.wordpress.org/simonwheatley/)
 *   [ jenkoian ](https://profiles.wordpress.org/jenkoian/)
 *   [ Boro Sitnikovski ](https://profiles.wordpress.org/bor0/)
 *   [ Andrija Vučinić ](https://profiles.wordpress.org/aidvu/)

“Memcached Object Cache” は6ロケールに翻訳されています。 [翻訳者](https://translate.wordpress.org/projects/wp-plugins/memcached/contributors)
のみなさん、翻訳へのご協力ありがとうございます。

[“Memcached Object Cache” をあなたの言語に翻訳しましょう。](https://translate.wordpress.org/projects/wp-plugins/memcached)

### 開発に興味がありますか ?

[コードを閲覧](https://plugins.trac.wordpress.org/browser/memcached/)するか、[SVN リポジトリ](https://plugins.svn.wordpress.org/memcached/)
をチェックするか、[開発ログ](https://plugins.trac.wordpress.org/log/memcached/)を
[RSS](https://plugins.trac.wordpress.org/log/memcached/?limit=100&mode=stop_on_copy&format=rss)
で購読してみてください。

## 変更履歴

#### 4.0.0

 * Add preemptive filter pre_wp_cache_get
 * Add flush_number replication to prevent accidental flush due to flush_number 
   eviction, server rotation, etc.

#### 3.2.2

 * Remove filter, and base key stripping on presence of `key_salt`

#### 3.2.1

 * Fix bug allowing **slow-ops** entries to have the same key, so toggling doesn’t
   work

#### 3.2.0

 * Better stats(). Now shows cache group/individual calls with size of the payload
   and timings.
 * PHP 5.6.20 is now required
 * Fix **get_multi** to show per group calls
 * Added filter **(memcached_strip_keys)** to bypass memcached key stripping
 * Special group for **slow-ops** ( > 5ms ) with backtrace

#### 3.1.0

 * Add **wp_cache_get_multi**
 * Add support for the **$found** parameter
 * Set a variable for $max_expiration to 30 days
 * Code style changes
 * Different coloring for unknown stats group
 * Store host/port on failure_callback
 * Default stats counts

#### 3.0.2

 * Better output of HTML

#### 3.0.1

 * Fix key generation error in switch_to_blog()

#### 3.0.0

 * Flush site cache by rotating keys
 * Flush global cache when flushing main site

#### 2.0.6

 * Flush the local cache on wp_cache_flush()

#### 2.0.5

 * Fix missing global in switch_to_blog

#### 2.0.4

 * Remove deprecated constructor

#### 2.0.3

 * Support for unix sockets

#### 2.0.2

 * Break references by cloning objects
 * Keep local cache in sync with memcached when using incr and decr
 * Handle limited environments where is_multisite() is not defined
 * Fix setting and getting 0
 * PHP 5.2.4 is now required
 * Use the WP_CACHE_KEY_SALT constant if available to guarantee uniqueness of keys

## メタ

 *  バージョン **4.0.0**
 *  最終更新日 **4年前**
 *  有効インストール数 **10+**
 *  WordPress バージョン ** 5.3またはそれ以降 **
 *  検証済み最新バージョン: **6.1.10**
 *  PHP バージョン ** 5.6.20またはそれ以降 **
 *  言語
 * [Chinese (China)](https://cn.wordpress.org/plugins/memcached/)、[Dutch (Belgium)](https://nl-be.wordpress.org/plugins/memcached/)、
   [English (UK)](https://en-gb.wordpress.org/plugins/memcached/)、[English (US)](https://wordpress.org/plugins/memcached/)、
   [German](https://de.wordpress.org/plugins/memcached/)、[Polish](https://pl.wordpress.org/plugins/memcached/)、
   [Russian](https://ru.wordpress.org/plugins/memcached/).
 *  [プラグインを翻訳](https://translate.wordpress.org/projects/wp-plugins/memcached)
 * タグ
 * [cache](https://ja.wordpress.org/plugins/tags/cache/)[memcached](https://ja.wordpress.org/plugins/tags/memcached/)
 *  [詳細を表示](https://ja.wordpress.org/plugins/memcached/advanced/)

## 評価

 5つ星中3.8つ星

 *  [  18 5-星レビュー     ](https://wordpress.org/support/plugin/memcached/reviews/?filter=5)
 *  [  1 4-星レビュー     ](https://wordpress.org/support/plugin/memcached/reviews/?filter=4)
 *  [  1 3-星レビュー     ](https://wordpress.org/support/plugin/memcached/reviews/?filter=3)
 *  [  0 2-星レビュー     ](https://wordpress.org/support/plugin/memcached/reviews/?filter=2)
 *  [  8 1-星レビュー     ](https://wordpress.org/support/plugin/memcached/reviews/?filter=1)

[Your review](https://wordpress.org/support/plugin/memcached/reviews/#new-post)

[すべてのレビューを見る](https://wordpress.org/support/plugin/memcached/reviews/)

## 貢献者

 *   [ Mark Jaquith ](https://profiles.wordpress.org/markjaquith/)
 *   [ Ryan Boren ](https://profiles.wordpress.org/ryan/)
 *   [ Matt Martz ](https://profiles.wordpress.org/sivel/)
 *   [ Andy Skelton ](https://profiles.wordpress.org/andy/)
 *   [ Andrew Nacin ](https://profiles.wordpress.org/nacin/)
 *   [ Barry ](https://profiles.wordpress.org/barry/)
 *   [ Erick Hitter ](https://profiles.wordpress.org/ethitter/)
 *   [ nickdaugherty ](https://profiles.wordpress.org/nickdaugherty/)
 *   [ Mohammad Jangda ](https://profiles.wordpress.org/batmoo/)
 *   [ Simon Wheatley ](https://profiles.wordpress.org/simonwheatley/)
 *   [ jenkoian ](https://profiles.wordpress.org/jenkoian/)
 *   [ Boro Sitnikovski ](https://profiles.wordpress.org/bor0/)
 *   [ Andrija Vučinić ](https://profiles.wordpress.org/aidvu/)

## サポート

意見や質問がありますか ?

 [サポートフォーラムを表示](https://wordpress.org/support/plugin/memcached/)