Tag: QueryPlanCache

All the articles with the tag "QueryPlanCache".

• The Real Cost of JPA Dirty Checking — readOnly, @DynamicUpdate, and Query Plan Cache Leaks

  4 May, 2026

  Hibernate's dirty checking copies an entity snapshot at load time and compares it against the current state at flush. With 10,000 rows, readOnly=true skips the snapshot copy (memory savings). @DynamicUpdate emits SQL with only the changed columns — but generates a fresh SQL string per update pattern, increasing Query Plan Cache usage (a permanent heap leak if hibernate.query.plan_cache_max_size is unset). @Modifying bulk JPQL is fastest but leaves the persistence context inconsistent — clearAutomatically=true is the standard. The clear() pattern (flush + clear every 50 inserts) keeps memory bounded for large insert batches. The trap in JPA is never one feature; it is the interaction of flush, cache, and snapshot lifecycle.