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SCRIPT LOAD

Loads a Lua script into the Redis server and returns its SHA1 hash.

Syntax​

SCRIPT LOAD script

Parameters​

  • script: The Lua script to be loaded into Redis. The script is provided as a string and should be a valid Lua code.

Details​

  • Available since: 2.6.0
  • Time complexity: O(N), where N is the length of the script.
  • ACL categories: @scripting

The SCRIPT LOAD command is used to load a Lua script into Redis. The script is stored in the server's script cache and is identified by its SHA1 hash. This hash can then be used with the EVALSHA command to execute the script. Loading a script into Redis does not execute it; it only stores it for future use.

Examples​

Loading a Script​

To load a Lua script into Redis:

SCRIPT LOAD "return redis.call('SET', 'key', 'value')"

This command loads the script into Redis and returns its SHA1 hash. The script sets the value of key to value.

Executing the Loaded Script​

  1. Load the script:

    SCRIPT LOAD "return redis.call('GET', 'key')"

  2. Note the SHA1 hash returned by the command.

  3. Execute the script using EVALSHA:

    EVALSHA <sha1> 1 key

Replace <sha1> with the SHA1 hash returned by SCRIPT LOAD. This will execute the script that retrieves the value of key.

Checking Script Existence​

To verify if a script is loaded, use:

SCRIPT EXISTS <sha1>

Replace <sha1> with the hash returned by SCRIPT LOAD. This will return 1 if the script is loaded, or 0 if it is not.

RESP2/RESP3 Reply​

  • Simple string reply: The SHA1 hash of the loaded script.

Example Reply​

"1a2b3c4d5e6f7g8h9i0j"

This SHA1 hash identifies the loaded script and can be used with EVALSHA for execution.

Notes​

  • Use SCRIPT LOAD to store scripts in Redis when you need to execute them frequently without sending the script text repeatedly.
  • The script is stored in the server's memory until it is removed with SCRIPT FLUSH or evicted.
  • Ensure that your Lua script is efficient and does not consume excessive memory or execution time.