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FCALL_RO

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FCALL_RO function numkeys [key [key ...]] [arg [arg ...]]
Group
Scripting and functions
Complexity
Depends on the function
Arity
-3 (at least 3 words, counting the command name)
Flags
slow, read-only
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FCALL_RO calls a function like FCALL, but only a function registered with the no-writes flag. Because the command is read-only, you can send it to read-only replicas and grant it to users who may not write.

Return value

Section titled “Return value”

The function’s return value, converted as described for EVAL.

Errors, in addition to those of FCALL:

  • ERR Can not execute a script with write flag using *_ro command. when the function was registered without no-writes.

Examples

Section titled “Examples”
127.0.0.1:6379> FUNCTION LOAD "#!lua name=readers\nredis.register_function{function_name='peek', callback=function(keys) return redis.call('GET', keys[1]) end, flags={'no-writes'}}"
"readers"
127.0.0.1:6379> SET greeting "hello"
OK
127.0.0.1:6379> FCALL_RO peek 1 greeting
"hello"

Compatibility

Section titled “Compatibility”

Same as Redis 7 and Valkey 8.

See also

Section titled “See also”

FCALL, EVAL_RO, FUNCTION LOAD