Title: memcache cache key length
Last modified: August 24, 2016

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# memcache cache key length

 *  Resolved [postme](https://wordpress.org/support/users/postme/)
 * (@postme)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/)
 * I ran into an issue with memcache which is related to wp-ffpc so I’d thought 
   to share it here in case it helps somebody else or might lead to a change in 
   wp-ffpc configugration.
 * The issue I had was caused by using the woocommerce social login plugin. When
   invoking the facebook OAuth login it would come back with very lengthy urls like:
 * `GET /wc-api/auth/facebook /int_callback?code=AQBXp9fIJ0bhu92R0IeP140baqfctKfO-
   Et9DnHuwBR-LK_AIejtGsc980ZiQ -y1IZZFlcxKeDqQjxc9VrLDQDDccEyEhenf-hBrW69mti588nYDGWz-
   yYJjnnsG9gWgOVMwfV8Gybe3z uEd4_POFKxpAZUxBGEi8KGkF6oUrr4FYVABoyh7DtpGN-MGO04xK0a481zgwxS7A_N3J-
   piFgY06rLLm 42xeixrfzO_VSS4M5VBR01jk5biFIgKhcfNNhXCKnaO2VqgE8DBGBi2-2_RG3GmOcJuX0DJly5uNFSwH
   rgnYR90x2qsuKGPl36aIco HTTP/1.1`
 * Which choked memcache with this error:
    `1283 memcached sent invalid response:"
   CLIENT_ERROR bad command line format"`
 * This is caused by wp-ffpc using the following key methodology:
 * `set $memcached_key data-$scheme://$host$request_uri;`
 * So the request url is used as a key and the returned url exceeds the constraints
   for memcache keys of 250 bytes.
 * The solution is to use a hashing algorithm to make a unique key based on the 
   original wp-ffpc scheme which looks like:
 * `set_sha1 $memcached_key data-$scheme://$host$request_uri;`
 * This makes sure that the generated key still follows the original naming convention
   data-$scheme://$host$request_uri but at the same time doesn’t exceed the key 
   length constraint of memcache.
 * Hope this helps anyone who runs into the same issue. It might be worthwhile to
   add to the wp-ffpc nginx config generator?
 * [https://wordpress.org/plugins/wp-ffpc/](https://wordpress.org/plugins/wp-ffpc/)

Viewing 8 replies - 1 through 8 (of 8 total)

 *  Plugin Author [petermolnar](https://wordpress.org/support/users/cadeyrn/)
 * (@cadeyrn)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975352)
 * Let me check if I can do this with nginx as well, not only PHP; in that case,
   it can go default, otherwise I’ll add it as option.
 *  Thread Starter [postme](https://wordpress.org/support/users/postme/)
 * (@postme)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975574)
 * sorry for the late reply, you probably have found the following by now yourself:
   
   [http://wiki.nginx.org/HttpSetMiscModule#set_sha1](http://wiki.nginx.org/HttpSetMiscModule#set_sha1)
   [http://wiki.nginx.org/HttpSetMiscModule#set_md5](http://wiki.nginx.org/HttpSetMiscModule#set_md5)
 * I’m using this from nginx without issues.
 *  Plugin Author [petermolnar](https://wordpress.org/support/users/cadeyrn/)
 * (@cadeyrn)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975580)
 * I’ve deployed the changes; currently testing them; it will be included in the
   next release, because so far it’s all fine.
 * Thank you very much for the links!
 *  [Oleksii Melnychuk](https://wordpress.org/support/users/melal/)
 * (@melal)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975581)
 * Just refused and uninstalled WP-FFPC plugin from my sites after v.1.8.1 was released
   due to necessity to use Nginx ngx_set_misc module. Usually on my servers I use
   Apache as backend and Nginx as frontend. Additionally Nginx grabs data from memcached
   directly. Since latest WP-FFPC was released user has been forced to use module
   ngx_set_misc which isn’t a part of Nginx stable release distributed as pre-build
   packages for Linux systems. It’s not acceptable for me to use at production infrastructure
   any kind of releases besides this Nginx pre-build packages from stable repository.
   As well as it is not convenient to build Nginx from source (as important security
   updates become real head ache).
 * Moreover new SHA1 decoding/encoding feature consumes more server CPU resources.
   Please, remove sha1 URLs encoding from WP-FFPC or provide to user a possibility
   to select between clear text and encoded URLs.
 *  Plugin Author [petermolnar](https://wordpress.org/support/users/cadeyrn/)
 * (@cadeyrn)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975582)
 * May I ask which package on which distribution are we talking about? Debian has
   at least 4 nginx packages.
 * I can make it an option, that is true.
 *  Plugin Author [petermolnar](https://wordpress.org/support/users/cadeyrn/)
 * (@cadeyrn)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975583)
 * There, in 1.8.2, sha1 is off by default; on by option.
 *  Thread Starter [postme](https://wordpress.org/support/users/postme/)
 * (@postme)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975584)
 * Wonderful, tnx Peter!
 *  [Oleksii Melnychuk](https://wordpress.org/support/users/melal/)
 * (@melal)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975585)
 * Dear Peter, thank you very much for your smart respond and good job – it’s really
   well done. I don’t know if Debian Nginx flavours include ngx_set_misc module,
   but I know definitely that every of Ubuntu nginx flavours (nginx-core, nginx-
   extras, nginx-full, nginx-light and nginx-naxsi) is compiled without this module.
   Read this kindly: [http://askubuntu.com/questions/553937/what-is-the-difference-between-the-core-full-extras-and-light-packages-for-ngi](http://askubuntu.com/questions/553937/what-is-the-difference-between-the-core-full-extras-and-light-packages-for-ngi)
 * In my message I talked Nginx native ‘stable’ (not ‘mainline’) release repository
   about, which is my favorite one due to its real stability: [http://nginx.org/packages/](http://nginx.org/packages/)
 * Thank you very much once again!

Viewing 8 replies - 1 through 8 (of 8 total)

The topic ‘memcache cache key length’ is closed to new replies.

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## Tags

 * [memcache](https://wordpress.org/support/topic-tag/memcache/)

 * 8 replies
 * 3 participants
 * Last reply from: [Oleksii Melnychuk](https://wordpress.org/support/users/melal/)
 * Last activity: [11 years, 1 month ago](https://wordpress.org/support/topic/memcache-cache-key-length/#post-5975585)
 * Status: resolved