How to cache results of a Spring Data JPA query method without using query cache?

The reason the code you have is not working is that @Cache is not intended to work that way. If you want to cache the results of a query method execution, the easiest way is to use Spring’s caching abstraction.

interface PromotionServiceXrefRepository extends PagingAndSortingRepository<PromotionServiceXref, Integer> {

  @Query("…")
  @Cacheable("servicesByCustomerId")
  Set<PromotionServiceXref> findByCustomerId(int customerId);

  @Override
  @CacheEvict(value = "servicesByCustomerId", key = "#p0.customer.id")
  <S extends PromotionServiceXref> S save(S service);
}

This setup will cause results of calls to findByCustomerId(…) be cached by the customer identifier. Note, that we added an @CacheEvict to the overridden save(…) method, so that the cache we populate with the query method is evicted, whenever an entity is saved. This probably has to be propagated to the delete(…) methods as well.

Now you can go ahead an configure a dedicated CacheManager (see the reference documentation for details) to plug in whichever caching solution you prefer (using a plain ConcurrentHashMap here).

 @Configuration
 @EnableCaching
 class CachingConfig {

   @Bean
   CacheManager cacheManager() {

     SimpleCacheManager cacheManager = new SimpleCacheManager();
     cacheManager.addCaches(Arrays.asList(new ConcurrentMapCache("servicesByCustomerId)));

     return cacheManager;
   }
 }