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@bkimble
Last active March 22, 2024 19:21
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List local memcached keys using Ruby
#!/usr/bin/env ruby
# List all keys stored in memcache.
# Credit to Graham King at http://www.darkcoding.net/software/memcached-list-all-keys/ for the original article on how to get the data from memcache in the first place.
require 'net/telnet'
headings = %w(id expires bytes cache_key)
rows = []
localhost = Net::Telnet::new("Host" => "localhost", "Port" => 11211, "Timeout" => 3)
matches = localhost.cmd("String" => "stats items", "Match" => /^END/).scan(/STAT items:(\d+):number (\d+)/)
slabs = matches.inject([]) { |items, item| items << Hash[*['id','items'].zip(item).flatten]; items }
longest_key_len = 0
slabs.each do |slab|
localhost.cmd("String" => "stats cachedump #{slab['id']} #{slab['items']}", "Match" => /^END/) do |c|
matches = c.scan(/^ITEM (.+?) \[(\d+) b; (\d+) s\]$/).each do |key_data|
cache_key, bytes, expires_time = key_data
rows << [slab['id'], Time.at(expires_time.to_i), bytes, cache_key]
longest_key_len = [longest_key_len,cache_key.length].max
end
end
end
row_format = %Q(|%8s | %28s | %12s | %-#{longest_key_len}s |)
puts row_format%headings
rows.each{|row| puts row_format%row}
localhost.close
@ginjo
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ginjo commented Jan 30, 2015

@bkimble thanks for this!

Here's yet another fork of your original gist:
https://gist.github.com/ginjo/aaa4a4395fcdbbad3d29

This revision adds a couple of features for working with cache item rows as ruby objects.

  • Isolates the cache item query and enumeration into a method that yields to an optional block (passing all elements of cache item. You can do anything with the block - print rows, return rows as an array of hashes, return a single 'matching' row, etc..
  • Accepts a list of servers and runs the above enumerator for all items found on every server.

I've included a method that mimics your original formatted printing, plus a method that returns all found cache items as an array of hashes.

@VARGA-Peter
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Unfortunately it does not work when the server has several 100 thousand keys...

@rafanasiev
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excellent, thanks a lot!

@rbalman
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rbalman commented Aug 18, 2017

Nice 😮 . I have customized this script for dump and restore using dalli gem.
https://gist.github.com/javanux/dbd005ef50ae4b8cea213af058abf771

@jsqu99
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jsqu99 commented Sep 5, 2017

I'm fairly certain this does not work on memcachier.

I successfully telneted in to our production servers and tried issues the stats cachedump command and got:

CLIENT_ERROR unsupported stats command

@vkdimitrov
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bingo! 👍

@ralphjay24
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ralphjay24 commented Apr 13, 2018

Thank you! This help me to solve problem of infinite caching(no expiration).

@archan937
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archan937 commented Oct 16, 2019

Hello, @bkimble. I have adjusted your Gist a bit, see: https://gist.github.com/archan937/f441146e1aeaa9da138e337514ee4000

The logic is in a method called keys and you can pass your memcached host (or a list of hosts) and an optional pattern to filter on keys.
Also, prints the slab IDs with all of its keys.

@ankhaa-g
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Unfortunately it does not work when the server has several 100 thousand keys...

Same here. Does not work with 60k keys.

@HeroProtagonist
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The require statement at the top needs to be updated because telnet was removed from the standard library at some point and made a separate gem. Otherwise script works as expected. Thanks @bkimble 👍

- require 'net/telnet'
+ gem 'net-telnet'

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