CODEWITHSUNDEEP
redis
ZedZip
ZedZip

Reputation: 6510

Redis: how to delete multiple keys matching pattern?

I need to remove 10 000 keys.

  1. What is better way: to exec this kind of script

    EVAL "return redis.call('del', unpack(redis.call('keys', ARGV[1])))" 0 "ROOT"

  2. May be better is to set expiration time and Redis will remove them? But how to do it in console using Lua script?

The script (see above) works because del comman dhas a format:

del key1 key2 ...

But Expire works only for 1 key.

Is it possible to do it in lua script?

For example: my application creates some search results cache and set for every page ttl = 3600. But user wants to clear cache immediately, i.e. delete all matching keys or set smaller expiration for them.

Upvotes: 8

Views: 27119

Answers (6)

originalhat
originalhat

Reputation: 1716

Here's how you can expire in bulk via the CLI:

EVAL 'for i, name in ipairs(redis.call("KEYS", <pattern>)) do redis.call("EXPIRE", name, 1); end' 0

Upvotes: 0

Merlin
Merlin

Reputation: 25709

redis-cli -h 127.0.0.1 -p 6379 --scan --pattern <pattern>* | xargs redis-cli unlink

Using scan and unlink are not blocking functions

Upvotes: 1

Dimitry
Dimitry

Reputation: 4593

I was looking all over for this ended up writing a bash script that takes in a host, port, and a pattern. Seems to work well. Here is the Gist.

if [ $# -ne 3 ] 
then
  echo "Delete keys from Redis matching a pattern using SCAN & DEL"
  echo "Usage: $0 <host> <port> <pattern>"
  exit 1
fi

cursor=-1
keys=""

while [ $cursor -ne 0 ]; do
  if [ $cursor -eq -1 ]
  then
    cursor=0
  fi

  reply=`redis-cli -h $1 -p $2 SCAN $cursor MATCH $3`
  cursor=`expr "$reply" : '\([0-9]*[0-9 ]\)'`
  if [[ $reply = *[[:space:]]* ]]
  then
    keys=${reply#[0-9]*[[:space:]]}
    for key in $keys; do
      echo "Delete the following key: $key"
      redis-cli -h $1 -p $2 DEL $key 
    done
  fi
done

Upvotes: 0

Raghavendra Acharya
Raghavendra Acharya

Reputation: 171

if you are trying to delete a key matching a prefix then you can try below command

redis-cli keys <PREFIX>'*' | xargs redis-cli del

here keys <PREFIX> '*' will give all the keys with matching prefix and then del command will delete all of them.

Upvotes: 8

Ganesh Krishnan
Ganesh Krishnan

Reputation: 7395

You can either use (from redis cli) to delete all keys:

flushall

or run this from your command line (bash)

redis-cli --scan --pattern aihello_user* | xargs redis-cli del

Upvotes: 13

Itamar Haber
Itamar Haber

Reputation: 50112

Whether you DEL or EXPIRE, once Lua script runs it will block other clients and if it runs for too long it the lua-time-limit timeout. Despite your reluctance for looping, I strongly recommend you do.

Expiry vs deletion may lessen some of the immediate load (yet to be empirically proven), so feel free to go with one or the other. In either case, use a client-side loop on a SCAN operation to invoke the command for each key. If you have a server/worker process somewhere in your architecture, you can consider delegating this task to it so the client will not be kept busy.

EDIT per comment: Variadic commands such as DEL are generally more performant than non-variadic commands, however here you're comparing two different operations so there are no assurances. The DEL approach is potentially more blocking because Redis will actually go ahead and delete the keys immediately - if you have a lot of keys to delete and/or their values are big, this could take more time. The EXPIRE approach tries to avoid this by leveraging on Redis' lazy expiry mechanism (it uses idle time to do so when possible), so the deletion-due-to-expiry load is theoretically better distributed. The best way to determine which works better for you is by testing both and comparing - I'd love to learn of your results!

Upvotes: 5

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