COMMAND · Valkey

COMMAND

Returns detailed information about all commands.

Usage

COMMAND

Description

Return an array with details about every Valkey command.

The COMMAND command is introspective. Its reply describes all commands that the server can process. Valkey clients can call it to obtain the server’s runtime capabilities during the handshake.

COMMAND also has several subcommands. Please refer to its subcommands for further details.

Cluster note: this command is especially beneficial for cluster-aware clients. Such clients must identify the names of keys in commands to route requests to the correct shard. Although most commands accept a single key as their first argument, there are many exceptions to this rule. You can call COMMAND and then keep the mapping between commands and their respective key specification rules cached in the client.

The reply it returns is an array with an element per command. Each element that describes a Valkey command is represented as an array by itself.

The command’s array consists of a fixed number of elements. The exact number of elements in the array depends on the server’s version.

  1. Name
  2. Arity
  3. Flags
  4. First key
  5. Last key
  6. Step
  7. ACL categories
  8. [Tips][tb]
  9. [Key specifications][td]
  10. Subcommands

Name

This is the command’s name in lowercase.

Note: Valkey command names are case-insensitive.

Arity

Arity is the number of arguments a command expects. It follows a simple pattern:

Command arity always includes the command’s name itself (and the subcommand when applicable).

Examples:

Flags

Command flags are an array. It can contain the following simple strings (status reply):

Movablekeys

Consider SORT:

1) 1) "sort"
   2) (integer) -2
   3) 1) write
      2) denyoom
      3) movablekeys
   4) (integer) 1
   5) (integer) 1
   6) (integer) 1
   ...

Some Valkey commands have no predetermined key locations or are not easy to find. For those commands, the movablekeys flag indicates that the first key, last key, and step values are insufficient to find all the keys.

Here are several examples of commands that have the movablekeys flag:

Valkey Cluster clients need to use other measures, as follows, to locate the keys for such commands.

You can use the COMMAND GETKEYS command and have your Valkey server report all keys of a given command’s invocation.

Clients can use the key specifications to identify the positions of key names. The only commands that require using COMMAND GETKEYS are SORT and MIGRATE for clients that parse keys’ specifications.

For more information, please refer to the [key specifications page][tr].

First key

The position of the command’s first key name argument. For most commands, the first key’s position is 1. Position 0 is always the command name itself.

Last key

The position of the command’s last key name argument. Valkey commands usually accept one, two or multiple number of keys.

Commands that accept a single key have both first key and last key set to 1.

Commands that accept two key name arguments, e.g. BRPOPLPUSH, SMOVE and RENAME, have this value set to the position of their second key.

Multi-key commands that accept an arbitrary number of keys, such as MSET, use the value -1.

Step

The step, or increment, between the first key and the position of the next key.

Consider the following two examples:

1) 1) "mset"
   2) (integer) -3
   3) 1) write
      2) denyoom
   4) (integer) 1
   5) (integer) -1
   6) (integer) 2
   ...
1) 1) "mget"
   2) (integer) -2
   3) 1) readonly
      2) fast
   4) (integer) 1
   5) (integer) -1
   6) (integer) 1
   ...

The step count allows us to find keys’ positions. For example MSET: Its syntax is MSET _key1_ _val1_ [key2] [val2] [key3] [val3]..., so the keys are at every other position (step value of 2). Unlike MGET, which uses a step value of 1.

ACL categories

This is an array of simple strings that are the ACL categories to which the command belongs. Please refer to the Access Control List page for more information.

Command tips

Helpful information about the command. To be used by clients/proxies.

Please check the [Command tips][tb] page for more information.

Key specifications

This is an array consisting of the command’s key specifications. Each element in the array is a map describing a method for locating keys in the command’s arguments.

For more information please check the [key specifications page][td].

Subcommands

This is an array containing all of the command’s subcommands, if any. Some Valkey commands have subcommands (e.g., the REWRITE subcommand of CONFIG). Each element in the array represents one subcommand and follows the same specifications as those of COMMAND’s reply.

Reply

Array reply: a nested list of command details. The order of the commands in the array is random.

Complexity

O(N) where N is the total number of commands

ACL Categories

@connection @slow

Examples

The following is COMMAND’s output for the GET command:

1)  1) "get"
    2) (integer) 2
    3) 1) readonly
       2) fast
    4) (integer) 1
    5) (integer) 1
    6) (integer) 1
    7) 1) @read
       2) @string
       3) @fast
    8) (empty array)
    9) 1) 1) "flags"
          2) 1) read
          3) "begin_search"
          4) 1) "type"
             2) "index"
             3) "spec"
             4) 1) "index"
                2) (integer) 1
          5) "find_keys"
          6) 1) "type"
             2) "range"
             3) "spec"
             4) 1) "lastkey"
                2) (integer) 0
                3) "keystep"
                4) (integer) 1
                5) "limit"
                6) (integer) 0
   10) (empty array)
...

History

See also

ACL, ACL CAT, ACL DELUSER, ACL DRYRUN, ACL GENPASS, ACL GETUSER, ACL HELP, ACL LIST, ACL LOAD, ACL LOG, ACL SAVE, ACL SETUSER, ACL USERS, ACL WHOAMI, BGREWRITEAOF, BGSAVE, COMMAND COUNT, COMMAND DOCS, COMMAND GETKEYS, COMMAND GETKEYSANDFLAGS, COMMAND HELP, COMMAND INFO, COMMAND LIST, CONFIG, CONFIG GET, CONFIG HELP, CONFIG RESETSTAT, CONFIG REWRITE, CONFIG SET, DBSIZE, DEBUG, FAILOVER, FLUSHALL, FLUSHDB, INFO, LASTSAVE, LATENCY, LATENCY DOCTOR, LATENCY GRAPH, LATENCY HELP, LATENCY HISTOGRAM, LATENCY HISTORY, LATENCY LATEST, LATENCY RESET, LOLWUT, MEMORY, MEMORY DOCTOR, MEMORY HELP, MEMORY MALLOC-STATS, MEMORY PURGE, MEMORY STATS, MEMORY USAGE, MODULE, MODULE HELP, MODULE LIST, MODULE LOAD, MODULE LOADEX, MODULE UNLOAD, MONITOR, PSYNC, REPLCONF, REPLICAOF, RESTORE-ASKING, ROLE, SAVE, SHUTDOWN, SLOWLOG, SLOWLOG GET, SLOWLOG HELP, SLOWLOG LEN, SLOWLOG RESET, SWAPDB, SYNC, TIME.