LUA Scripting

Lua Scripting

Lua is a powerful scripting language that is supported at the core of Redis. Lua scripts can be invoked dynamically by providing the script contents to Redis or used as stored procedure by loading the script into Redis and using its digest to invoke it.

String helloWorld = redis.eval("return ARGV[1]", STATUS, new String[0], "Hello World");

Using Lua scripts is straightforward. Consuming results in Java requires additional details to consume the result through a matching type. As we do not know what your script will return, the API uses call-site generics for you to specify the result type. Additionally, you must provide a ScriptOutputType hint to EVAL so that the driver uses the appropriate output parser. See Output Formats for further details.

Lua scripts can be stored on the server for repeated execution. Dynamically-generated scripts are an anti-pattern as each script is stored in Redis' script cache. Generating scripts during the application runtime may, and probably will, exhaust the host’s memory resources for caching them. Instead, scripts should be as generic as possible and provide customized execution via their arguments. You can register a script through SCRIPT LOAD and use its SHA digest to invoke it later:

String digest = redis.scriptLoad("return ARGV[1]", STATUS, new String[0], "Hello World");

// later
String helloWorld = redis.evalsha(digest, STATUS, new String[0], "Hello World");