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fix: send mget to replica even if there's only 1 value #8715

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Merged
carodewig merged 4 commits into from
Dec 4, 2025
Merged

fix: send mget to replica even if there's only 1 value #8715

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5bb456c
fix: send mget to replica even if there's only 1 value
carodewig Dec 4, 2025
f90b295
test: fix test to check single key
carodewig Dec 4, 2025
42b81ca
Merge branch 'dev' into caroline/fix-single-mget-fetch
carodewig Dec 4, 2025
c58e3d9
lint: fix fmt
carodewig Dec 4, 2025
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17 changes: 5 additions & 12 deletions apollo-router/src/cache/redis.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -665,19 +665,11 @@ impl RedisCacheStorage {
/// because `NotFound` shouldn't be considered an error.
pub(crate) async fn get_multiple_with_options<K: KeyType, V: ValueType>(
&self,
mut keys: Vec<RedisKey<K>>,
keys: Vec<RedisKey<K>>,
options: Options,
) -> Result<Vec<Result<RedisValue<V>, RedisError>>, RedisError> {
tracing::trace!("getting multiple values from redis: {:?}", keys);
let client = self.client();

if keys.len() == 1 {
let key = self.make_key(keys.swap_remove(0));
let res_value: Result<RedisValue<V>, RedisError> =
client.with_options(&options).get(key).await;
let value = res_value.inspect_err(|e| self.record_error(e))?;
Ok(vec![Ok(value)])
} else if self.is_cluster {
if self.is_cluster {
// we cannot do an MGET across hash slots (error: "ERR CROSSSLOT Keys in request don't
// hash to the same slot").
// we either need to group the keys by hash slot, or just send a GET for each key; given
Expand All @@ -687,7 +679,7 @@ impl RedisCacheStorage {

// then we query all the key groups at the same time
// use `client.replicas()` since we're in a cluster and can take advantage of read-replicas
let client = client.replicas().with_options(&options);
let client = self.client().replicas().with_options(&options);
let mut tasks = Vec::with_capacity(len);
for (index, key) in keys.into_iter().enumerate() {
let client = client.clone();
Expand All @@ -709,7 +701,8 @@ impl RedisCacheStorage {
.into_iter()
.map(|k| self.make_key(k))
.collect::<Vec<_>>();
let values: Vec<Option<RedisValue<V>>> = client
let values: Vec<Option<RedisValue<V>>> = self
.client()
.with_options(&options)
.mget(keys)
.await
Expand Down
26 changes: 15 additions & 11 deletions apollo-router/tests/integration/redis.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1793,25 +1793,29 @@ async fn test_redis_doesnt_use_replicas_in_standalone_mode() {
assert!(redis_monitor_output.command_sent_to_any("GET"));
}

// NB: the `num_products` parameter determines how many `Product` entities will be requested from
// the `reviews` subgraph. This is useful to check that `get_multiple` works properly with different
// numbers of keys.
#[rstest::rstest]
#[tokio::test(flavor = "multi_thread")]
async fn test_redis_uses_replicas_in_clusters_for_mgets() {
async fn test_redis_uses_replicas_in_clusters_for_mgets(#[values(1, 3, 5)] num_products: usize) {
if !graph_os_enabled() {
return;
}

let router_config = include_str!("fixtures/response_cache_redis_cluster.router.yaml");
let mut subgraph_overrides = HashMap::new();

let products = [
json!({"__typename":"Product","upc":"1","name":"Table","reviews":[{"id":"review1"}]}),
json!({"__typename":"Product","upc":"2","name":"Chair","reviews":[{"id":"review2"}]}),
json!({"__typename":"Product","upc":"3","name":"Desk","reviews":[{"id":"review3"}]}),
json!({"__typename":"Product","upc":"4","name":"Lamp","reviews":[{"id":"review4"}]}),
json!({"__typename":"Product","upc":"5","name":"Sofa","reviews":[{"id":"review5"}]}),
];

let products_response = ResponseTemplate::new(200)
.set_body_json(serde_json::json! {{"data": {
"topProducts": [
{"__typename":"Product","upc":"1","name":"Table","reviews":[{"id":"review1"}]},
{"__typename":"Product","upc":"2","name":"Chair","reviews":[{"id":"review2"}]},
{"__typename":"Product","upc":"3","name":"Desk","reviews":[{"id":"review3"}]},
{"__typename":"Product","upc":"4","name":"Lamp","reviews":[{"id":"review4"}]},
{"__typename":"Product","upc":"5","name":"Sofa","reviews":[{"id":"review5"}]}
]
}}})
.set_body_json(serde_json::json! {{"data": {"topProducts": products[..num_products]}}})
.insert_header("cache-control", "max-age=500, public");

let reviews_response = ResponseTemplate::new(200)
Expand Down Expand Up @@ -1899,7 +1903,7 @@ async fn test_redis_uses_replicas_in_clusters_for_mgets() {
let parse_error = r#"apollo_router_cache_redis_errors_total{error_type="parse""#;
router.assert_metrics_does_not_contain(parse_error).await;

let example_cache_key = "version:1.1:subgraph:reviews:type:Product:representation:ddf7d062949ffde207db2ced05093a823d64730d30fac573d6168f13cc8080c5:hash:739583f793fb842194e6be6c6f126df63cc0ee86f8702745ac4630521ab6752d:data:070af9367f9025bd796a1b7e0cd1335246f658aa4857c3a4d6284673b7d07fa6";
let example_cache_key = "version:1.1:subgraph:reviews:type:Product:representation:dd668a3ba05fb2fcd9e372b7063fe717f3ff1c209c29fa8367b8324e49775115:hash:739583f793fb842194e6be6c6f126df63cc0ee86f8702745ac4630521ab6752d:data:070af9367f9025bd796a1b7e0cd1335246f658aa4857c3a4d6284673b7d07fa6";
router
.assert_redis_cache_contains(example_cache_key, None)
.await;
Expand Down