FCALL_RO
Invokes a registered function through the read-only path.
Lua & functions · Example verified
Syntax covered here
FCALL_RO function numkeys keyLoad the library first; the verified function declares no-writes and uses GET on its supplied key.
Tested example & replies
Requests below run in order against an empty database. Each connection authenticates with the fixture password first. Quoted values are strings; null is a nil reply; arrays preserve RESP order.
# connection: default
> FUNCTION FLUSH
"OK"
# connection: default
> FUNCTION LOAD "#!lua name=manual\nredis.register_function{function_name='read_value', callback=function(keys,args) return redis.call('GET',keys[1]) end, flags={'no-writes'}}"
"manual"
# connection: default
> SET sample value
"OK"
# connection: default
> fcall_ro read_value 1 sample
"value"Test environment & reproducible evidence
Verified: 2026-09-21T11:06:06Z · Docker / Linux aarch64 · lavik 0.1.0-beta.1
Storage & connection: io_uring · temporary file, 2 workers, standalone, plaintext TCP, password authentication. This test does not measure NVMe performance.
Pinned source: 3955b98d43b312324aa8d52775df52cfb111c0d0
Binary SHA-256: 8306b37ddf05023f85166a6aa2192b7084757e8defd342b602e6470244aca887
Image: sha256:af0cfb11b78f184cb6cc49a774a49dc97a8e43a0bd3f4d63d83c8c9ef3282d6e
Lavik command registry · Valkey counterpart (support may differ)