CacheStore cannot be used on the worker node! cache_set was

Error message

CacheStore cannot be used on the worker node! cache_set was used.

What it means

ClusterCacheStoreClient (worker-node CacheStore) panics on cache_set because workers must not write to the local cache store directly. Cache item creation/updates must be performed on the master node or via the cluster-distributed path. The panic names the offending method to make the misroute obvious.

Source

Thrown at rust/cubestore/cubestore/src/cachestore/cache_rocksstore.rs:1953

}

crate::di_service!(RocksCacheStore, [CacheStore]);
crate::di_service!(CacheStoreRpcClient, [CacheStore]);

pub struct ClusterCacheStoreClient {}

#[async_trait]
impl CacheStore for ClusterCacheStoreClient {
    async fn cache_all(&self, _limit: Option<usize>) -> Result<Vec<IdRow<CacheItem>>, CubeError> {
        panic!("CacheStore cannot be used on the worker node! cache_all was used.")
    }

    async fn cache_set(
        &self,
        _item: CacheItem,
        _update_if_not_exists: bool,
    ) -> Result<bool, CubeError> {
        panic!("CacheStore cannot be used on the worker node! cache_set was used.")
    }

    async fn cache_clear(&self) -> Result<(), CubeError> {
        panic!("CacheStore cannot be used on the worker node! cache_clear was used.")
    }

    async fn truncate(&self) -> Result<(), CubeError> {
        panic!("CacheStore cannot be used on the worker node! truncate was used.")
    }

    async fn cache_delete(&self, _key: String) -> Result<(), CubeError> {
        panic!("CacheStore cannot be used on the worker node! cache_delete was used.")
    }

    async fn cache_get(&self, _key: String) -> Result<Option<IdRow<CacheItem>>, CubeError> {
        panic!("CacheStore cannot be used on the worker node! cache_get was used.")
    }

View on GitHub (pinned to 7d981676b3)

Solutions

Send cache_set operations to the master node or use the cluster-aware cache client.
Review node role configuration; make the writer a master or enable the proper cache delegation path.
In code, resolve the CacheStore via the cluster/metastore so writes are delegated, not aimed at the worker stub.

Example fix

// before
worker_cache_store.cache_set(item, true).await?; // panics on worker
// after
cluster_cache_client.cache_set(item, true).await?; // delegated via master

Defensive patterns

Strategy: validation

Validate before calling

if node_role() == Role::Worker {
    return Err(CubeError::internal("cache_set is master-only"));
}
cache_store.cache_set(item, true).await?;

Type guard

fn can_mutate_cache(store: &dyn CacheStore) -> bool {
    std::any::Any::type_id(store) != std::any::TypeId::of::<ClusterCacheStoreClient>()
}

Try / catch

if std::any::TypeId::of::<ClusterCacheStoreClient>() == store_type_id() {
    return Err(CubeError::internal("cache_set must be routed via the master node"));
}
cache_store.cache_set(item, update_if_not_exists).await?;

Prevention

Route cache writes through the master or cluster delegation API
Inject the correct CacheStore implementation based on node role
Never broadcast cache writes to every cluster node
Add role checks before invoking CacheStore mutation methods

When it happens

Trigger: Calling cache_set(item, update_if_not_exists) on a worker node's ClusterCacheStoreClient — e.g. result-cache write logic executed on a worker that assumed local cache ownership.

Common situations: Worker node receiving cache-write traffic intended for the master; misconfigured load balancing; custom tooling invoking cache APIs against a worker endpoint.

Related errors

AI-assisted analysis of cube-js/cube@7d981676b3 (2026-09-02). Data as JSON: /api/errors/76fc3387a0590a30. Report an issue: GitHub.