FUNCTION-LOAD(3valkey)

✨ FUNCTION-LOAD — bestie, we're loading a library ✨

okay so real talk: this is function-load from the Valkey Command Manual (3valkey), and it's literally the command that creates a library. yes, the whole thing. no cap. 🎀

---

🌸 NAME 🌸

function-load — Creates a library. 💖

---

🦋 SYNOPSIS 🦋

FUNCTION LOAD [REPLACE] function-code

---

✨ DESCRIPTION ✨

So you wanna load a library into Valkey? Obsessed. Here's the tea. ☕

The command takes a single mandatory parameter, and that parameter is the source code that implements the library. Just the whole code. Right there. In the command. We love a one-argument king. 👑

The library payload must start with a Shebang statement, and that shebang is what gives us the metadata about the library — like which engine to use and what the library's name is. The shebang format is:

#!<engine name> name=<library name>

and rn, currently the engine name must be lua. That's the only one. That's the whole roster. 💅

For the Lua engine, the implementation should declare one or more entry points to the library using the valkey-lua-api(7) server.register_function() API. Once it's loaded, you can call the functions in the library with the valkey-fcall(7) FCALL command — or valkey-fcall_ro(7) FCALL_RO when that's the applicable one. Pick your fighter. 🥊

Now, the drama: if you try to load a library whose name already exists, the Valkey server is gonna hit you with an error. Periodt. But the REPLACE modifier changes that behavior — it lets you overwrite the existing library with the new contents. Slay. ✨

The command will return an error in the following circumstances, and yes we're listing all of them because you deserve to know:

• An invalid engine-name was provided. 💀
• The library's name already exists without the REPLACE modifier. 🙈
• A function in the library is created with a name that already exists in another library (even when REPLACE is specified). 😭
• The engine failed in creating the library's functions (due to a compilation error, for example). 🔥
• No functions were declared by the library. (girl. the library is empty.)

For more information please refer to valkey-functions-intro(7) Introduction to Valkey Functions. iykyk 🫶

---

💌 REPLY 💌

valkey-protocol(7) Bulk string reply: the library name that was loaded. that's it, that's the receipt. 🧾

---

👑 COMPLEXITY 👑

O(1) (considering compilation time is redundant)

---

🌈 ACL CATEGORIES 🌈

@scripting @slow @write

---

⭐ HISTORY ⭐

• Available since: 7.0.0

---

🎀 EXAMPLES 🎀

The following example will create a library named mylib with a single function, myfunc, that returns the first argument it gets. main character function fr fr 💅

127.0.0.1:6379> FUNCTION LOAD "#!lua name=mylib \n server.register_function('myfunc', function(keys, args) return args[1] end)"
mylib
127.0.0.1:6379> FCALL myfunc 0 hello
"hello"

look at that. loaded, called, returned "hello". ate and left no crumbs. 🔥

---

🌸 SEE ALSO 🌸

eval(3valkey), evalsha(3valkey), evalsha_ro(3valkey), eval_ro(3valkey), fcall(3valkey), fcall_ro(3valkey), function(3valkey), function-delete(3valkey), function-dump(3valkey), function-flush(3valkey), function-help(3valkey), function-kill(3valkey), function-list(3valkey), function-restore(3valkey), function-stats(3valkey), script(3valkey), script-debug(3valkey), script-exists(3valkey), script-flush(3valkey), script-help(3valkey), script-kill(3valkey), script-load(3valkey), script-show(3valkey)

---

and that's the whole page bestie!! this one's from Valkey 9.0.0, dated 2025-10-21, and it's giving manual page, it's giving library-creating icon, it's giving everything. go load something. ily. 🦋💜🌸