Make queryPlanStoreKey a hash of both the query and operationName (…

…#2310)

.changeset/fluffy-toes-deliver.md

@@ -0,0 +1,8 @@
+---
+"@apollo/gateway": patch
+---
+
+Previously the `queryPlanStoreKey` was a hash of the query concatenated with an unhashed `operationName` if it was present. This resulted in variable length cache keys that could become unnecessarily long, occupying additional space in the query plan cache.
+
+This change incorporates the `operationName` _into_ the hash itself (if `operationName` is present).
+

gateway-js/src/index.ts

@@ -4,7 +4,7 @@ import type { Logger } from '@apollo/utils.logger';
 import LRUCache from 'lru-cache';
 import {
   GraphQLSchema,
-  VariableDefinitionNode,
+  VariableDefinitionNode
 } from 'graphql';
 import { buildOperationContext, OperationContext } from './operationContext';
 import {
@@ -750,7 +750,9 @@ export class ApolloGateway implements GatewayInterface {
       async (span) => {
         try {
           const { request, document, queryHash } = requestContext;
-          const queryPlanStoreKey = queryHash + (request.operationName || '');
+          const queryPlanStoreKey = request.operationName ?
+            createHash('sha256').update(queryHash).update(request.operationName).digest('hex')
+            : queryHash;
           const operationContext = buildOperationContext({
             schema: this.schema!,
             operationDocument: document,