hibernate/hibernate-orm · error · UnsupportedOperationException

The function {name} is not an aggregate function

Error message

The function {name} is not an aggregate function

What it means

Every SQM function descriptor carries a FunctionKind (NORMAL, AGGREGATE, ORDERED_SET_AGGREGATE, WINDOW). When the query requests an aggregate-shaped expression — classically a FILTER clause — the engine calls generateSqmAggregateFunctionExpression; if the descriptor's kind is not AGGREGATE it throws UnsupportedOperationException naming the function. Non-aggregate functions cannot take a FILTER clause.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/query/sqm/function/AbstractSqmSelfRenderingFunctionDescriptor.java:114

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

	@Override
	public <T> SelfRenderingSqmAggregateFunction<T> generateSqmAggregateFunctionExpression(
			List<? extends SqmTypedNode<?>> arguments,
			SqmPredicate filter,
			ReturnableType<T> impliedResultType,
			QueryEngine queryEngine) {
		if ( functionKind != FunctionKind.AGGREGATE ) {
			throw new UnsupportedOperationException( "The function " + getName() + " is not an aggregate function" );
		}
		return new SelfRenderingSqmAggregateFunction<>(
				this,
				this,
				arguments,
				filter,
				impliedResultType,
				getArgumentsValidator(),
				getReturnTypeResolver(),
				queryEngine.getCriteriaBuilder(),
				getName()
		);
	}

	@Override
	public <T> SelfRenderingSqmOrderedSetAggregateFunction<T> generateSqmOrderedSetAggregateFunctionExpression(
			List<? extends SqmTypedNode<?>> arguments,
			SqmPredicate filter,

View on GitHub (pinned to fad1729dce)

Solutions

1. Use a genuine aggregate function with the FILTER clause (sum, count, avg, min, max, or a registered UDAF).
2. For your own aggregate function, register the descriptor with FunctionKind.AGGREGATE (constructor argument / registerAlternateKey on a descriptor built with the aggregate kind).
3. If the filter was meant as a WHERE restriction on a scalar expression, move it into the WHERE clause instead.

Example fix

// before
List<Long> r = em.createQuery("select count(p.id) filter (where p.active) from Person p", Long.class) // ok
        .getResultList();
// but: 'upper(p.name) filter (where p.active)' -> UnsupportedOperationException

// after — custom aggregate registered with the right kind
queryEngine.getSqmFunctionRegistry().register(
    "my_agg",
    new NamedSqmFunctionDescriptor("my_agg", null, null, FunctionKind.AGGREGATE,
        ArgumentRenderingStrategy.STANDARD, "my_agg(?1) filter (where ?2)"));

org.hibernate.query.sqm.function.SqmFunctionDescriptor f =
    sessionFactory.getQueryEngine().getSqmFunctionRegistry().findFunction("my_func");
if (f == null || f.getFunctionKind() != org.hibernate.query.sqm.function.FunctionKind.AGGREGATE) {
    // do not use 'my_func(...) filter (where ...)' — pick a registered aggregate or re-register with FunctionKind.AGGREGATE
}

try { em.createQuery(ql, Long.class).getResultList(); } catch (UnsupportedOperationException e) { /* 'not an aggregate function': replace with sum/count/... or register the descriptor with FunctionKind.AGGREGATE */ throw e; }

When it happens

Trigger: HQL or Criteria using '<nonAggregateFunc>(...) filter (where ...)' — e.g. 'select upper(p.name) filter (where p.active) from Person p'; or a custom function registered without FunctionKind.AGGREGATE (default NORMAL) then used with a filter clause. The exception is raised while building the SQM expression, i.e. at query creation/interpretation time.

Common situations: Custom dialect functions registered via NamedSqmFunctionDescriptor / SqmFunctionRegistry without passing FunctionKind.AGGREGATE, then used with FILTER; typos where an aggregate was intended (sum vs concat); expecting a UDAF wrapper to be treated as an aggregate automatically.

Related errors

• The function {name} is not an ordered set-aggregate function
• The function {name} is not a window function
• Can't emulate filter clause for inverse distribution functio
• Can't emulate filter clause for inverse distribution functio
• Entity discriminator cannot be de-referenced

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/4a7127dffa336858. Report an issue: GitHub.