hibernate/hibernate-orm · error · UnsupportedOperationException

The function {name} is not a window function

Error message

The function {name} is not a window function

What it means

OVER (...) window syntax requires the function descriptor to be of FunctionKind.WINDOW. When a non-window function is used with an OVER clause, generateSqmWindowFunctionExpression throws UnsupportedOperationException stating the function is not a window function. This guards SQL validity — scalar functions cannot be windowed.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/query/sqm/function/AbstractSqmSelfRenderingFunctionDescriptor.java:162

				withinGroupClause,
				impliedResultType,
				getArgumentsValidator(),
				getReturnTypeResolver(),
				queryEngine.getCriteriaBuilder(),
				getName()
		);
	}

	@Override
	protected <T> SelfRenderingSqmWindowFunction<T> generateSqmWindowFunctionExpression(
			List<? extends SqmTypedNode<?>> arguments,
			SqmPredicate filter,
			Boolean respectNulls,
			Boolean fromFirst,
			ReturnableType<T> impliedResultType,
			QueryEngine queryEngine) {
		if ( functionKind != FunctionKind.WINDOW ) {
			throw new UnsupportedOperationException( "The function " + getName() + " is not a window function" );
		}
		return new SelfRenderingSqmWindowFunction<>(
				this,
				this,
				arguments,
				filter,
				respectNulls,
				fromFirst,
				impliedResultType,
				getArgumentsValidator(),
				getReturnTypeResolver(),
				queryEngine.getCriteriaBuilder(),
				getName()
		);
	}

	public static boolean filterClauseSupported(SqlAstTranslator<?> translator) {
		return translator.getSessionFactory().getJdbcServices().getDialect().supportsFilterClause();

View on GitHub (pinned to fad1729dce)

Solutions

1. Use a real window function: row_number(), rank(), dense_rank(), lead(), lag(), first_value(), nth_value(), etc.
2. Register your custom window function with FunctionKind.WINDOW in its descriptor (e.g. NamedSqmFunctionDescriptor constructor).
3. If the OVER clause was a mistake, remove it; if you need raw window SQL Hibernate cannot express, use a native query.

Example fix

// before
em.createQuery("select concat(e.name, '') over (partition by e.dept) from Employee e"); // UnsupportedOperationException

// after
em.createQuery("select rowNumber() over (partition by e.dept order by e.salary) from Employee e");

var f = sessionFactory.getQueryEngine().getSqmFunctionRegistry().findFunction("my_func");
if (f == null || f.getFunctionKind() != org.hibernate.query.sqm.function.FunctionKind.WINDOW) {
    // 'my_func(...) over (...)' will fail — use rowNumber/rank/lead/lag or register with FunctionKind.WINDOW
}

try { em.createQuery(ql).getResultList(); } catch (UnsupportedOperationException e) { /* 'not a window function': use a registered window function or re-register the descriptor with FunctionKind.WINDOW */ throw e; }

When it happens

Trigger: HQL/Criteria like 'select concat(e.name, '-x') over (partition by e.dept) from Employee e', or 'myFunc(a) over (order by b)' where myFunc was registered as NORMAL/AGGREGATE without WINDOW kind. Raised during SQM interpretation, before SQL generation.

Common situations: Custom dialect functions (string or math helpers) used experimentally with OVER; expecting any aggregate with OVER to route through the window path (built-in aggregates are already registered appropriately, user ones are not); porting raw SQL window queries into HQL verbatim.

Related errors

• The function {name} is not an aggregate function
• The function {name} is not an ordered set-aggregate function
• Can't emulate [%s] in clause %s. Only the SELECT clause is s
• Can't emulate [%s] in clause %s. Only the SELECT clause is s
• Entity discriminator cannot be de-referenced

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/59c3854c579460db. Report an issue: GitHub.