HHH-19826 Add array_reverse and array_sort functions #11391

yybmion · 2025-12-05T15:43:58Z

Implements array_reverse() and array_sort() HQL functions.

array_reverse(array) - Returns reversed array
array_sort(array [, descending [, nulls_first]]) - Returns sorted array
- Default: ASC, NULLs last
- Follows PostgreSQL 18 semantics

All database tests pass.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license
and can be relicensed under the terms of the LGPL v2.1 license in the future at the maintainers' discretion.
For more information on licensing, please check here.

https://hibernate.atlassian.net/browse/HHH-19826

Implement array_reverse() and array_sort() with PostgreSQL 18 semantics. Supports PostgreSQL, H2, HSQLDB, Oracle, and CockroachDB with native functions or SQL emulation as appropriate. Signed-off-by: Yoobin Yoon <yunyubin54@gmail.com>

hibernate-github-bot · 2025-12-05T15:44:05Z

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beikov

This looks quite good already. I left a couple of comments.

beikov · 2025-12-08T14:32:20Z

hibernate-core/src/main/java/org/hibernate/dialect/function/CommonFunctionFactory.java

+						StandardArgumentsValidators.composite(
+								StandardArgumentsValidators.between( 1, 3 ),
+								ArrayArgumentValidator.DEFAULT_INSTANCE
+						)


Suggested change

StandardArgumentsValidators.composite(

StandardArgumentsValidators.between( 1, 3 ),

ArrayArgumentValidator.DEFAULT_INSTANCE

)

new ArgumentTypesValidator(

StandardArgumentsValidators.composite(

StandardArgumentsValidators.between( 1, 3 ),

ArrayArgumentValidator.DEFAULT_INSTANCE

),

FunctionParameterType.ANY,

FunctionParameterType.BOOLEAN,

FunctionParameterType.BOOLEAN

)

beikov · 2025-12-08T14:33:21Z

...rnate-core/src/main/java/org/hibernate/dialect/function/array/AbstractArraySortFunction.java

+				StandardArgumentsValidators.composite(
+						StandardArgumentsValidators.between( 1, 3 ),
+						ArrayArgumentValidator.DEFAULT_INSTANCE
+				),


Suggested change

StandardArgumentsValidators.composite(

StandardArgumentsValidators.between( 1, 3 ),

ArrayArgumentValidator.DEFAULT_INSTANCE

),

new ArgumentTypesValidator(

StandardArgumentsValidators.composite(

StandardArgumentsValidators.between( 1, 3 ),

ArrayArgumentValidator.DEFAULT_INSTANCE

),

FunctionParameterType.ANY,

FunctionParameterType.BOOLEAN,

FunctionParameterType.BOOLEAN

)

beikov · 2025-12-08T14:34:39Z

...rnate-core/src/main/java/org/hibernate/dialect/function/array/AbstractArraySortFunction.java

+						StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE,
+						StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE


Also need to pass the TypeConfiguration in the constructor:

Suggested change

StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE,

StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE

StandardFunctionArgumentTypeResolvers.invariant( typeConfiguration, FunctionParameterType.BOOLEAN ),

StandardFunctionArgumentTypeResolvers.invariant( typeConfiguration, FunctionParameterType.BOOLEAN )

beikov · 2025-12-08T14:35:11Z

hibernate-core/src/main/java/org/hibernate/dialect/function/CommonFunctionFactory.java

+								StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE,
+								StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE


Suggested change

StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE,

StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE

StandardFunctionArgumentTypeResolvers.invariant( typeConfiguration, FunctionParameterType.BOOLEAN ),

StandardFunctionArgumentTypeResolvers.invariant( typeConfiguration, FunctionParameterType.BOOLEAN )

beikov · 2025-12-08T14:42:51Z

hibernate-core/src/main/java/org/hibernate/query/criteria/HibernateCriteriaBuilder.java

+	 * @since 7.2
+	 */
+	@Incubating
+	<T> JpaExpression<List<T>> collectionReverse(Expression<? extends Collection<T>> collectionExpression);


Since we're going to return something of the same type as passed as argument, this signature seems more correct to me. I'd love to use SequencedCollection as type bound, but that is unfortunately only part of Java 21 and Hibernate ORM 7 still supports Java 17, so we will have to live with Collection, though I don't think there are expectations around sorting/reversing when passing something that isn't ordered. We could do a dynamic check of the argument Java type in the argument type validator though if you like.

Suggested change

<T> JpaExpression<List<T>> collectionReverse(Expression<? extends Collection<T>> collectionExpression);

<C extends Collection<?>> JpaExpression<C> collectionReverse(Expression<C> collectionExpression);

beikov · 2025-12-08T14:50:07Z

hibernate-core/src/main/java/org/hibernate/dialect/type/OracleUserDefinedTypeExporter.java

+						"else " +
+						"v_nulls_first := p_nulls_first; " +
+						"end if; " +
+						"for i in 1 .. v_count - 1 loop " +


Please take inspiration from this article to let the SQL engine do the sorting: https://technology.amis.nl/oracle/sorting-plsql-collections-the-quite-simple-way-part-two-have-the-sql-engine-do-the-heavy-lifting/

beikov · 2025-12-08T14:52:10Z

...te-core/src/main/java/org/hibernate/dialect/function/array/PostgreSQLArraySortEmulation.java

+
+		sqlAppender.append( ") from unnest(" );
+		arrayExpression.accept( walker );
+		sqlAppender.append( ") with ordinality t(val,idx))," );


It looks like this implementation doesn't need ordinality.

Suggested change

sqlAppender.append( ") with ordinality t(val,idx))," );

sqlAppender.append( ") t(val))," );

beikov · 2025-12-08T14:56:45Z

...core/src/main/java/org/hibernate/dialect/function/array/PostgreSQLArrayReverseEmulation.java

+		sqlAppender.append( "coalesce((select array_agg(t.val order by t.idx desc) from unnest(" );
+		arrayExpression.accept( walker );
+		sqlAppender.append( ") with ordinality t(val,idx))," );
+
+		arrayExpression.accept( walker );
+		sqlAppender.append( ")" );


Why do you need a coalesce wrapper? I see that you pass an empty array in the other emulations, so I wonder if PostgreSQL fails to infer the type of the array[] expression here? Did you also test with PostgreSQL 17?

Suggested change

sqlAppender.append( "coalesce((select array_agg(t.val order by t.idx desc) from unnest(" );

arrayExpression.accept( walker );

sqlAppender.append( ") with ordinality t(val,idx))," );

arrayExpression.accept( walker );

sqlAppender.append( ")" );

sqlAppender.append( "(select array_agg(t.val order by t.idx desc) from unnest(" );

arrayExpression.accept( walker );

sqlAppender.append( ") with ordinality t(val,idx))" );

beikov · 2025-12-08T15:04:29Z

hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArraySortFunction.java

+			final SqlAstNode descNode = sqlAstArguments.get( 1 );
+			if ( descNode instanceof Literal literal && literal.getLiteralValue() instanceof Boolean boolValue ) {
+				sqlAppender.append( boolValue ? '1' : '0' );
+			}
+			else {
+				descNode.accept( walker );
+			}
+
+			if ( sqlAstArguments.size() > 2 ) {
+				sqlAppender.append( ',' );
+				final SqlAstNode nullsNode = sqlAstArguments.get( 2 );
+				if ( nullsNode instanceof Literal literal && literal.getLiteralValue() instanceof Boolean boolValue ) {
+					sqlAppender.append( boolValue ? '1' : '0' );
+				}
+				else {
+					nullsNode.accept( walker );
+				}
+			}


Suggested change

final SqlAstNode descNode = sqlAstArguments.get( 1 );

if ( descNode instanceof Literal literal && literal.getLiteralValue() instanceof Boolean boolValue ) {

sqlAppender.append( boolValue ? '1' : '0' );

}

else {

descNode.accept( walker );

}

if ( sqlAstArguments.size() > 2 ) {

sqlAppender.append( ',' );

final SqlAstNode nullsNode = sqlAstArguments.get( 2 );

if ( nullsNode instanceof Literal literal && literal.getLiteralValue() instanceof Boolean boolValue ) {

sqlAppender.append( boolValue ? '1' : '0' );

}

else {

nullsNode.accept( walker );

}

}

final Expression descNode = (Expression) sqlAstArguments.get( 1 );

sqlAppender.append( "case when " );

descNode.accept( walker );

sqlAppender.append( '=' );

var sessionFactory = walker.getSessionFactory();

castNonNull( descNode.getExpressionType() ).getSingleJdbcMapping().getJdbcLiteralFormatter()

.appendJdbcLiteral( sqlAppender, true, sessionFactory.getJdbcServices().getDialect(), sessionFactory.getWrapperOptions() );

sqlAppender.append( " then 1 else 0 end" );

if ( sqlAstArguments.size() > 2 ) {

sqlAppender.append( ",case when " );

final Expression nullsNode = (Expression) sqlAstArguments.get( 2 );

nullsNode.accept( walker );

sqlAppender.append( '=' );

castNonNull( nullsNode.getExpressionType() ).getSingleJdbcMapping().getJdbcLiteralFormatter()

.appendJdbcLiteral( sqlAppender, true, sessionFactory.getJdbcServices().getDialect(), sessionFactory.getWrapperOptions() );

sqlAppender.append( " then 1 else 0 end" );

}

beikov · 2025-12-08T15:17:02Z

...te-core/src/main/java/org/hibernate/dialect/function/array/PostgreSQLArraySortEmulation.java

+
+		final SqlAstNode arrayExpression = sqlAstArguments.get( 0 );
+
+		final boolean descending = sqlAstArguments.size() > 1


Unfortunately, this will not work if the argument is passed as e.g. parameter. The same comment applies to the emulations for H2 and HSQLDB.

I know it's not great, but you could have this specialized branch for when the arguments are literals, and have a general implementation that produces something like this:

order by case when <nulls-first> then (case when t.val is null then 0 else 1 end) else (case when t.val is null then 1 else 0 end) end, case when <descending> then t.val end desc, case when not <descending> then t.val end

The <nulls-first> and <descending> placeholders are to be filled with sqlAstArguments.get( 1 ) and sqlAstArguments.get( 2 ) respectively.

Maybe this can be simplified further, but I didn't give this a lot of thought.

beikov requested changes Dec 8, 2025

View reviewed changes

		StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE,
		StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE

	<T> JpaExpression<List<T>> collectionReverse(Expression<? extends Collection<T>> collectionExpression);
	<C extends Collection<?>> JpaExpression<C> collectionReverse(Expression<C> collectionExpression);

	sqlAppender.append( ") with ordinality t(val,idx))," );
	sqlAppender.append( ") t(val))," );


		final SqlAstNode arrayExpression = sqlAstArguments.get( 0 );

		final boolean descending = sqlAstArguments.size() > 1

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HHH-19826 Add array_reverse and array_sort functions #11391

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HHH-19826 Add array_reverse and array_sort functions #11391

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yybmion commented Dec 5, 2025 •

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