hibernate/hibernate-orm · error · IllegalArgumentException

"Unsupported aggregate SQL type: " + aggregateColumnTypeCode

Error message

"Unsupported aggregate SQL type: " + aggregateColumnTypeCode

What it means

Error ""Unsupported aggregate SQL type: " + aggregateColumnTypeCode" thrown in hibernate/hibernate-orm.

Source

Thrown at hibernate-core/src/main/java/org/hibernate/dialect/aggregate/H2AggregateSupport.java:104

								// We encode binary data as hex, so we have to decode here
								return template.replace(
										placeholder,
										"(select array_agg(" + hexDecodeExpression( queryExpression( readExpression + "[i.x]" ), elementTypeName ) + ") from system_range(1,10000) i where i.x<=coalesce(array_length(" + readExpression + "),0))"
								);
							default:
								return template.replace(
										placeholder,
										"(select array_agg(" + valueExpression( readExpression + "[i.x]", elementTypeName ) + ") from system_range(1,10000) i where i.x<=coalesce(array_length(" + readExpression + "),0))"
								);
						}
					default:
						return template.replace(
								placeholder,
								valueExpression( readExpression, getCastTypeName( column, typeConfiguration ) )
						);
				}
		}
		throw new IllegalArgumentException( "Unsupported aggregate SQL type: " + aggregateColumnTypeCode );
	}

	private static String hexDecodeExpression(String valueExpression, String columnType) {
		return "cast(hextoraw(regexp_replace(" + valueExpression + ",'([0-9a-f][0-9a-f])','00$1')) as " + columnType + ")";
	}

	private static String valueExpression(String valueExpression, String columnType) {
		return "cast(" + queryExpression( valueExpression ) + " as " + columnType + ')';
	}

	private static String queryExpression(String valueExpression) {
		// First we produce a SQL null if we see a JSON null
		// Next, we replace quotes that surround the value
		// Finally, we undo escaping that was done to a string
		return "stringdecode(regexp_replace(nullif(" + valueExpression + ",JSON'null'),'^\"(.*)\"$','$1'))";
	}

	private static String jsonCustomWriteExpression(String customWriteExpression, JdbcMapping jdbcMapping) {

View on GitHub (pinned to fad1729dce)

Solutions

1. Map the aggregate column with a supported SQL type (JSON/ARRAY).
2. Avoid the unsupported aggregate type on H2.

When it happens

Trigger: Triggered when the application calls a Hibernate dialect feature that the configured database dialect cannot provide: Unsupported aggregate SQL type (H2).

Common situations: Common when running against a database whose dialect lacks this capability, when a mapping or HQL/Criteria query requests unsupported functionality, or when the wrong dialect is configured for the database in use. Error: Unsupported aggregate SQL type (H2).

AI-assisted analysis of hibernate/hibernate-orm@fad1729dce (2026-08-22). Data as JSON: /api/errors/6f8240e55b5da111. Report an issue: GitHub.