Filter the fetches we add to a batch when we create the batch

.changesets/fix_garypen_router_243_batch_fetch_filter.md

@@ -0,0 +1,9 @@
+### Filter the fetches we add to a batch when we create the batch ([PR #5034](https://github.com/apollographql/router/pull/5034))
+
+Without filtering the query hashes during batch creation we could end up in a situation where we have additional query hashes in the batch.
+
+This manifests itself by batch queries failing with query hashes appearing as committed without ever having been registered in a batch.
+
+Filtering during batch creation is now matching the filtering at subgraph coordination and fixes this issue.
+
+By [@garypen](https://github.com/garypen) in https://github.com/apollographql/router/pull/5034

apollo-router/src/query_planner/plan.rs

@@ -9,6 +9,7 @@ use serde::Serialize;
 pub(crate) use self::fetch::OperationKind;
 use super::fetch;
 use super::subscription::SubscriptionNode;
+use crate::configuration::Batching;
 use crate::error::CacheResolverError;
 use crate::json_ext::Object;
 use crate::json_ext::Path;
@@ -77,10 +78,12 @@ impl QueryPlan {
 
     pub(crate) fn query_hashes(
         &self,
+        batching_config: Batching,
         operation: Option<&str>,
         variables: &Object,
     ) -> Result<Vec<Arc<QueryHash>>, CacheResolverError> {
-        self.root.query_hashes(operation, variables, &self.query)
+        self.root
+            .query_hashes(batching_config, operation, variables, &self.query)
     }
 }
 
@@ -216,6 +219,7 @@ impl PlanNode {
     /// details and don't use _ so that future node types must be handled here.
     pub(crate) fn query_hashes(
         &self,
+        batching_config: Batching,
         operation: Option<&str>,
         variables: &Object,
         query: &Query,
@@ -236,8 +240,10 @@ impl PlanNode {
                         new_targets.extend(nodes);
                     }
                     PlanNode::Fetch(node) => {
-                        // If requires.is_empty() we can batch it!
-                        if node.requires.is_empty() {
+                        // If requires.is_empty() we may be able to batch it!
+                        if node.requires.is_empty()
+                            && batching_config.batch_include(&node.service_name)
+                        {
                             query_hashes.push(node.schema_aware_hash.clone());
                         }
                     }

apollo-router/src/services/supergraph/service.rs

@@ -254,9 +254,10 @@ async fn service_call(
                     return Ok(response);
                 }
                 // Now perform query batch analysis
-                let batching = context.extensions().lock().get::<BatchQuery>().cloned();
-                if let Some(batch_query) = batching {
-                    let query_hashes = plan.query_hashes(operation_name.as_deref(), &variables)?;
+                let batch_query_opt = context.extensions().lock().get::<BatchQuery>().cloned();
+                if let Some(batch_query) = batch_query_opt {
+                    let query_hashes =
+                        plan.query_hashes(batching, operation_name.as_deref(), &variables)?;
                     batch_query
                         .set_query_hashes(query_hashes)
                         .await