EVALSHA_RO - Upstash Documentation

Use EVALSHA_RO to run a script cached by its SHA1 digest. The script may not write to the database. It is the read-only form of EVALSHA: any write command called from the script fails, which lets the server run it on replicas. As with EVALSHA, a digest that is not in the cache produces a NOSCRIPT error, and the caller is expected to fall back to EVAL_RO with the script body. Read-only scripts take the global lock like any other script unless the cached body’s shebang sets the allow-key-locking flag, for example #!lua flags=no-writes,allow-key-locking. With the flag, the call takes shared read locks on the keys passed in KEYS. See Key-Based Locking.

Syntax

EVALSHA_RO <sha1> <numkeys> [<key> [<key> ...]] [<arg> [<arg> ...]]

Arguments

Argument	Required	Repeatable	Description
`<sha1>`	Yes	No	SHA1 digest of a script cached with `SCRIPT LOAD`.
`<numkeys>`	Yes	No	Number of key arguments that follow.
`<key>`	No	Yes	Redis key targeted by the command.
`<arg>`	No	Yes	Additional argument, available to the script as `ARGV`.

Important points

numkeys must equal the number of key arguments that immediately follow it; remaining arguments are available to the script or function as ordinary arguments.
A read-only script still takes the global lock unless the cached body’s shebang sets the allow-key-locking flag. See Key-Based Locking.
Pass every key the script reads through KEYS whether or not allow-key-locking is set. A key built inside the script is read from disk under the lock when it is not in memory, and it is rejected outright when the flag is set. See Dynamic Keys and Latency.

Response

The reply reports the result of the operation. Error replies have the same shape in RESP2 and RESP3 and are surfaced as exceptions by the SDKs below.

Protocol	Reply
RESP2	Reply produced by the cached read-only script
RESP3	Reply produced by the cached read-only script

Client libraries often decode bulk strings, maps, sets, and numeric strings into language-native values. The table describes the Redis wire reply.

Examples

TCP examples use the TLS REDIS_URL from the Upstash console. REST examples use UPSTASH_REDIS_REST_URL and UPSTASH_REDIS_REST_TOKEN.

Redis CLI

EVALSHA_RO fb67a0c03b48ddbf8b4c9b011e779563bdbc28cb 0 value

@upstash/redis

import { Redis } from "@upstash/redis";

const redis = Redis.fromEnv();

const result = await redis.evalshaRo("fb67a0c03b48ddbf8b4c9b011e779563bdbc28cb", [], ["hello"]);
console.log(result) // "hello"

upstash_redis

from upstash_redis import Redis

redis = Redis.from_env()
result = redis.evalsha_ro("<sha1>", args=["value"])
print(result)

ioredis

import Redis from "ioredis";

const redis = new Redis(process.env.REDIS_URL!);
const result = await redis.evalsha_ro("<sha1>", "0", "value");
console.log(result);

node-redis

import { createClient } from "redis";

const client = await createClient({ url: process.env.REDIS_URL })
  .on("error", console.error)
  .connect();
const result = await client.evalShaRo("<sha1>", { arguments: ["value"] });
console.log(result);

redis-py

import os
import redis

client = redis.from_url(os.environ["REDIS_URL"])
result = client.evalsha_ro("<sha1>", 0, "value")
print(result)

go-redis

package main

import (
    "context"
    "fmt"
    "os"

    "github.com/redis/go-redis/v9"
)

func main() {
    opts, err := redis.ParseURL(os.Getenv("REDIS_URL"))
    if err != nil {
        panic(err)
    }
    client := redis.NewClient(opts)
    result, err := client.EvalShaRO(context.Background(), "<sha1>", nil, "value").Result()
    if err != nil {
        panic(err)
    }
    fmt.Println(result)
}

jedis

import java.net.URI;

import redis.clients.jedis.Jedis;

try (Jedis jedis = new Jedis(new URI(System.getenv("REDIS_URL")))) {
  Object result = jedis.evalshaReadonly("<sha1>", java.util.List.of(), java.util.List.of("value"));
  System.out.println(result);
}

redis-rs

fn main() -> redis::RedisResult<()> {
    let url = std::env::var("REDIS_URL").expect("REDIS_URL is not set");
    let client = redis::Client::open(url)?;
    let mut connection = client.get_connection()?;

    let mut command = redis::cmd("EVALSHA_RO");
    command.arg("<sha1>");
    command.arg("1");
    let result: redis::Value = command.query(&mut connection)?;
    println!("{result:?}");
    Ok(())
}

​Syntax

​Arguments

​Important points

​Response

​Examples

Syntax

Arguments

Important points

Response

Examples