FUNCTION LOAD

Creates a library.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	FUNCTION LOAD
Catalog group	Scripting commands
Upstream since	7.0.0 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

FUNCTION LOAD [REPLACE] function-code

ffkv behavior and limits

Sandboxed Lua 5.1 is bounded to 1 million instructions, 32 MiB Lua memory, 64 nesting levels, 8 MiB scripts/bridge values/replies, 10,000 bridge calls and 16 MiB cumulative bridge arguments. Writes before runtime errors commit. The volatile SHA cache holds 256 scripts/16 MiB with FIFO eviction; durable function libraries cap at 256 and one 16 MiB encoded WAL frame.

Source: README.md:426–449; tests/bdd/features/scripting.feature.

All requests share the 8 MiB framing/1,024-argument ingress limit; normal RESP replies have 64 MiB wire/logical budgets with bounded nesting/value counts. Management and Lua origins impose smaller budgets. These are not a process RSS cap. Catalog inclusion is not exhaustive option or wire-format parity. See limits and compatibility.

Upstream metadata

The following fields come from the pinned Redis metadata, not measured ffkv performance or an assertion that ffkv enforces every upstream flag. Running COMMAND INFO/COMMAND DOCS describe the current engine.

Upstream Redis complexity: O(1) (considering compilation time is redundant)

Upstream arity: -3 (includes the command name; a negative number is a minimum).

Command flags: NOSCRIPT, WRITE, DENYOOM.

ACL categories: SCRIPTING.

Command tips: REQUEST_POLICY:ALL_SHARDS, RESPONSE_POLICY:ALL_SUCCEEDED.

Argument structure

Argument	Type	Constraints / metadata
replace	pure-token	optional; token: REPLACE
function-code	string	Required

Additional pinned upstream metadata

{
  "group": "scripting",
  "since": "7.0.0"
}

Metadata source · Local snapshot: src/command_metadata.json, key function|load.

BDD coverage and source examples

These are source observations, not a test run performed by this documentation build. A tag identifies scenario intent; an extracted vector identifies a command invocation, which may intentionally produce an error. Scenarios may require setup, multiple connections, persistence, cluster nodes or native-module fixtures.

• Function and search metadata accompany migrated keys without replacing unrelated catalogs — tests/bdd/features/cluster.feature:1011; invocation observed.
• Dynamic Lua and function keys cannot diverge from their authoritative cluster owner — tests/bdd/features/cluster.feature:1279; invocation observed.
• Named callbacks share local helpers and expose registration metadata — tests/bdd/features/scripting.feature:123; command tag and invocation observed.
• Invalid replacement cannot discard the previous library — tests/bdd/features/scripting.feature:177; command tag and invocation observed.
• Function containers restore with append replace and flush policies — tests/bdd/features/scripting.feature:211; invocation observed.
• Libraries survive crash recovery but invalid containers cannot alter them — tests/bdd/features/scripting.feature:302; command tag and invocation observed.
• Function engine statistics reflect load delete and idle cancellation — tests/bdd/features/scripting.feature:338; invocation observed.
• An executing readonly function is observable and can actually be interrupted — tests/bdd/features/scripting.feature:508; invocation observed.
• A function that has written cannot be killed and retains its completed effects — tests/bdd/features/scripting.feature:538; invocation observed.
• Replace policy cannot steal functions owned by a different library — tests/bdd/features/scripting.feature:568; command tag and invocation observed.
• A no-writes declaration is enforced rather than trusted — tests/bdd/features/scripting.feature:597; invocation observed.
• Each outer Lua invocation owns a fresh import session rather than borrowing network layouts — tests/bdd/features/scripting.feature:623; invocation observed.
• Library source and optional metadata roundtrip through WITHCODE — tests/bdd/features/scripting.feature:684; command tag and invocation observed.

Extracted command vectors

The following JSON arrays are the test harness’s argument vectors, not shell commands. Numeric arguments are converted by the harness; objects of the form {"base64":"…"} represent decoded binary bytes, not a literal JSON command argument. Preserve scenario setup and connection ordering. See the CLI guide for shell quoting and binary stdin. No reply is invented or inferred.

Function and search metadata accompany migrated keys without replacing unrelated catalogs — tests/bdd/features/cluster.feature:1021 (node “node2” executes:)

[
  "FUNCTION",
  "LOAD",
  "#!lua name=destination_functions\nredis.register_function{function_name='local_answer',flags={'no-writes'},callback=function() return 42 end}"
]

Next source assertion: the reply equals:

"destination_functions"

Named callbacks share local helpers and expose registration metadata — tests/bdd/features/scripting.feature:126 (I execute:)

[
  "FUNCTION",
  "LOAD",
  "#!lua name=inventory\nlocal call = redis.call\nlocal function get(keys) return call('GET', keys[1]) end\nredis.register_function{function_name='inventory_get',callback=get,flags={'no-writes'},description='Read an item'}"
]

Next source assertion: the reply equals:

"inventory"

Dynamic Lua and function keys cannot diverge from their authoritative cluster owner — tests/bdd/features/cluster.feature:1343 (node “node1” executes:)

[
  "FUNCTION",
  "LOAD",
  "#!lua name=dynamic\nredis.register_function{function_name='dynamic_get',callback=function(keys,args) return redis.pcall('GET',args[1]) end,flags={'no-writes','allow-cross-slot-keys'}}\nredis.register_function{function_name='dynamic_put',callback=function(keys,args) return redis.pcall('SET',args[1],args[2]) end,flags={'allow-cross-slot-keys'}}"
]

Next source assertion: the reply equals:

"dynamic"