get all keys set in memcached

Question

How can I get all the keys set in my memcached instance s    I tried googling  but didn t find much except that PHP supports a getAllKeys method  which means it is actually possible to do this somehow  How can I get the same within a telnet session   I have tried out all the retrieval related options mentioned in memcached cheat sheet and Memcached telnet command summary  but none of them work and I am at a loss to find the correct way to do this   Note  I am currently doing this in development  so it can be assumed that there will be no issues due to new keys being set or other such race conditions happening  and the number of keys will also be limited

User · Answer

If you have PHP  amp  PHP-memcached installed  you can run    php -r   c   new Memcached     c- gt addServer  localhost   11211   var dump   c- gt getAllKeys

User · Answer

memdump  There is a memcdump  sometimes memdump  command for that  part of libmemcached-tools   e g    memcdump --servers localhost   which will return all the keys     memcached-tool  In the recent version of memcached there is also memcached-tool command  e g   memcached-tool localhost 11211 dump   less   which dumps all keys and values   See also    What  39 s the simplest way to get a dump of all memcached keys into a file  How do I view the data in memcache

User · Answer

Found a way  thanks to the link here  with the original google group discussion here   First  Telnet to your server   telnet 127 0 0 1 11211   Next  list the items to get the slab ids    stats items STAT items 3 number 1 STAT items 3 age 498 STAT items 22 number 1 STAT items 22 age 498 END   The first number after    items    is the slab id  Request a cache dump for each slab id  with a limit for the max number of keys to dump    stats cachedump 3 100 ITEM views decorators cache cache header  cc7d9  6 b  1256056128 s  END  stats cachedump 22 100 ITEM views decorators cache cache page  8427e  7736 b  1256056128 s  END

User · Answer

The easiest way is to use python-memcached-stats package  https   github com abstatic python-memcached-stats  The keys   method should get you going   Example -  from memcached stats import MemcachedStats mem   MemcachedStats    mem keys     key-1     key-2     key-3

User · Answer

Base on  mu   answer here  I ve written a cache dump script   The script dumps all the content of a memcached server  It s tested with Ubuntu 12 04 and a localhost memcached  so your milage may vary      usr bin env bash  echo  stats items       nc localhost 11211      grep -oe    0-9          grep -oe   0-9         sort      uniq      xargs -L1 -I   bash -c  echo  stats cachedump    1000    nc localhost 11211    What it does  it goes through all the cache slabs and print 1000 entries of each   Please be aware of certain limits of this script i e  it may not scale for a 5GB cache server for example  But it s useful for debugging purposes on a local machine

User · Answer

Bash To get list of keys in Bash  follow the these steps  First  define the following wrapper function to make it simple to use  copy and paste into shell   function memcmd       exec  memcache  lt  gt  dev tcp localhost 11211   printf  quot  s n s n quot   quot    quot  quit  gt  amp   memcache    cat  lt  amp   memcache      Memcached 1 4 31 and above You can use lru crawler metadump all command to dump  most of  the metadata for  all of  the items in the cache   As opposed to cachedump  it does not cause severe performance problems and has no limits on the amount of keys that can be dumped   Example command by using the previously defined function  memcmd lru crawler metadump all  See  ReleaseNotes1431   Memcached 1 4 30 and below Get list of slabs by using items statistics command  e g   memcmd stats items  For each slub class  you can get list of items by specifying slub id along with limit number  0 - unlimited   memcmd stats cachedump 1 0 memcmd stats cachedump 2 0 memcmd stats cachedump 3 0 memcmd stats cachedump 4 0      Note  You need to do this for each memcached server  To list all the keys from all stubs  here is the one-liner  per one server   for id in   memcmd stats items   grep -o  quot   0-9     quot    tr -d     sort -nu   do     memcmd stats cachedump  id 0 done  Note  The above command could cause severe performance problems while accessing the items  so it s not advised to run on live   Notes   stats cachedump only dumps the HOT LRU  IIRC    which is managed by a background thread as activity happens  This means under a new enough version which the 2Q algo enabled  you ll get snapshot views of what s in just one of the LRU s  If you want to view everything  lru crawler metadump 1  or lru crawler metadump all  is the new mostly-officially-supported method that will asynchronously dump as many keys as you want  you ll get them out of order but it hits all LRU s  and unless you re deleting replacing items multiple runs should yield the same results   Source  GH-405   Related   List all objects in memcached Writing a Redis client in pure bash  it s Redis  but very similar approach  Check other available commands at https   memcached org wiki Check out the protocol txt docs file

[get] get all keys set in memcached

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