CODEWITHSUNDEEP
redis
help652
help652

Reputation: 11

How to delete a key if key has a value

I use Redis. I want to delete a key key1 if it has the value value1. I have find this command :

DEL key1

but not :

DEL key1 value1

Upvotes: 1

Views: 2935

Answers (1)

Stephen Jennings
Stephen Jennings

Reputation: 13234

Redis doesn't have an atomic command for this, but you can build it yourself.

The simplest case would be to GET followed by DEL, but it introduces a race condition if another connection changes key1 between the two commands:

GET key1

# then, if it matches the value you care about:
DEL key1

If you can use Lua scripting, then you can do it in one Redis command:

EVAL "if redis.call('get', KEYS[1]) == ARGV[1] then redis.call('del', KEYS[1]) end" 1 key1 value1

If you can't use Lua scripting, then you can use transactions, but it will take multiple commands:

WATCH key1
GET key1

# if the value matches (the EXEC call will fail if anything changed key1):
MULTI
DEL key1
EXEC

# if it doesn't:
UNWATCH key1

Upvotes: 1

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