hibernate/hibernate-orm · error · HibernateException

Duplicate row was found and `%s` was specified

Error message

Duplicate row was found and `%s` was specified

What it means

Thrown by ListResultsConsumer.readUniqueAssert when a query runs under UniqueSemantic.ASSERT: every row read must be distinct, and results.addUnique detected a row equal (per the result JavaType) to one already collected. ASSERT is applied primarily by the internal by-id load plan (SingleIdLoadPlan uses ASSERT when a single result is expected), i.e. `EntityManager.find`/`session.find`, and only when the row reader has no collection initializers. Genuine duplicates for a primary-key load mean the mapping does not guarantee one row per id.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/sql/results/spi/ListResultsConsumer.java:262

			RowReader<R> rowReader,
			Results<R> results) {
		int readRows = 0;
		while ( rowProcessingState.next() ) {
			results.add( rowReader.readRow( rowProcessingState ) );
			rowProcessingState.finishRowProcessing( true );
			readRows++;
		}
		return readRows;
	}

	private static <R> int readUniqueAssert(
			RowProcessingStateStandardImpl rowProcessingState,
			RowReader<R> rowReader,
			Results<R> results) {
		int readRows = 0;
		while ( rowProcessingState.next() ) {
			if ( !results.addUnique( rowReader.readRow( rowProcessingState ) ) ) {
				throw new HibernateException(
						String.format(
								Locale.ROOT,
								"Duplicate row was found and `%s` was specified",
								UniqueSemantic.ASSERT
						)
				);
			}
			rowProcessingState.finishRowProcessing( true );
			readRows++;
		}
		return readRows;
	}

	private static <R> int readUnique(
			RowProcessingStateStandardImpl rowProcessingState,
			RowReader<R> rowReader,
			Results<R> results) {
		int readRows = 0;

View on GitHub (pinned to fad1729dce)

Solutions

1. Fix the underlying data or mapping so at most one row exists per primary key (dedupe the view/table, add the missing unique constraint)
2. For JOINED inheritance, delete the duplicate id rows from the extra subclass table(s) so each id lives in exactly one subclass
3. Fix custom `@Loader`/`@SQLSelect` SQL to return a unique row (add the right predicate or `distinct` on the id)
4. As a stopgap, load via a query with `UniqueSemantic`-tolerant semantics (e.g. a plain JPQL `where e.id = :id`) instead of `find()` to observe the duplicates, then fix the data

Example fix

// before: entity mapped to a view with duplicate ids -> em.find throws
Employee e = em.find(Employee.class, id);
// after: dedupe the view (SQL) so each id appears once, keep em.find
create view employee_v as select distinct on (id) * from employee_raw;

// Prove the load key is unique before relying on em.find (e.g. for view-backed entities)
Long cnt = em.createQuery("select count(*) from EmployeeViewBacked e where e.businessKey = :k", Long.class)
             .setParameter("k", key).getSingleResult();
if (cnt != 1) throw new IllegalStateException("Load key not unique: " + key + " (" + cnt + " rows)");

catch (org.hibernate.HibernateException e) { if (e.getMessage() != null && e.getMessage().contains("Duplicate row was found")) { /* data issue: dedupe, fix view/inheritance/custom loader */ } throw e; }

When it happens

Trigger: `em.find(Employee.class, id)` where the entity is mapped to a database view containing the id twice; JOINED inheritance with the same id present in two subclass tables; a custom `@Loader`/`@SQLSelect` returning the same id more than once; broken data where a 'unique' key used for loading is not actually unique.

Common situations: Read-only reporting entities mapped onto views without a unique key; denormalized tables feeding entity mappings; data corruption or manual inserts breaking subclass-table uniqueness; custom loader SQL with an accidental cross join duplicating rows.

Related errors

• No add primary key syntax supported by SQLiteDialect
• SingleStore does not support altering primary key.
• No row with the given identifier exists for entity " + infoS
• Cannot add primary key constraint in Cloud Spanner.
• Dialect returns null TemporaryTableStrategy for temporary ta

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/28cb8f070122219a. Report an issue: GitHub.