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Redis command to get all available keys?

Is there a Redis command for fetching all keys in the database? I have seen some python-redis libraries fetching them. But was wondering if it is possible from redis-client.

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Lalith Avatar asked Mar 09 '11 21:03

Lalith


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Which Redis command is used to obtain all the keys in a database?

The Redis KEYS command returns all the keys in the database that match a pattern (or all the keys in the key space). Similar commands for fetching all the fields stored in a hash is HGETALL and for all fetching the members of a SMEMBERS. The keys in Redis themselves are stored in a dictionary (aka a hash table).

How can I get total number of keys in Redis?

The first command you can use to get the total number of keys in a Redis database is the DBSIZE command. This simple command should return the total number of keys in a selected database as an integer value. The above example command shows that there are 203 keys in the database at index 10.

How can I check Redis data?

A Redis server has 16 databases by default. You can check the actual number by running redis-cli config get databases. In interactive mode, the database number is displayed in the prompt within square braces. For example, 127.0. 0.1:6379[13] shows that the 13th database is in use.

How many keys can Redis store?

Redis can handle up to 2^32 keys, and was tested in practice to handle at least 250 million keys per instance. Every hash, list, set, and sorted set, can hold 2^32 elements. In other words your limit is likely the available memory in your system.


2 Answers

Try to look at KEYS command. KEYS * will list all keys stored in redis.

EDIT: please note the warning at the top of KEYS documentation page:

Time complexity: O(N) with N being the number of keys in the database, under the assumption that the key names in the database and the given pattern have limited length.

UPDATE (V2.8 or greater): SCAN is a superior alternative to KEYS, in the sense that it does not block the server nor does it consume significant resources. Prefer using it.

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yojimbo87 Avatar answered Oct 07 '22 09:10

yojimbo87


Updated for Redis 2.8 and above

As noted in the comments of previous answers to this question, KEYS is a potentially dangerous command since your Redis server will be unavailable to do other operations while it serves it. Another risk with KEYS is that it can consume (dependent on the size of your keyspace) a lot of RAM to prepare the response buffer, thus possibly exhausting your server's memory.

Version 2.8 of Redis had introduced the SCAN family of commands that are much more polite and can be used for the same purpose.

The CLI also provides a nice way to work with it:

$ redis-cli --scan --pattern '*' 
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Itamar Haber Avatar answered Oct 07 '22 11:10

Itamar Haber