Fix a few more test issues and handle group by summarization rendering strategies as well as group by literal rendering strategies

hibernate-core/src/main/java/org/hibernate/dialect/AbstractHANADialect.java

@@ -1538,4 +1538,9 @@ public abstract class AbstractHANADialect extends Dialect {
 	protected abstract boolean supportsAsciiStringTypes();
 
 	protected abstract Boolean useUnicodeStringTypesDefault();
+
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.EMPTY_GROUPING;
+	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/AbstractTransactSQLDialect.java

@@ -20,6 +20,7 @@ import org.hibernate.query.spi.QueryEngine;
 import org.hibernate.query.sqm.mutation.internal.idtable.AfterUseAction;
 import org.hibernate.query.sqm.mutation.internal.idtable.IdTable;
 import org.hibernate.query.sqm.mutation.internal.idtable.LocalTemporaryTableStrategy;
+import org.hibernate.query.sqm.mutation.internal.idtable.TempIdTableExporter;
 import org.hibernate.query.sqm.mutation.spi.SqmMultiTableMutationStrategy;
 
 import java.sql.CallableStatement;
@@ -217,14 +218,24 @@ abstract class AbstractTransactSQLDialect extends Dialect {
 		return "select getdate()";
 	}
 
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.COLUMN_REFERENCE;
+	}
+
 	@Override
 	public SqmMultiTableMutationStrategy getFallbackSqmMutationStrategy(
 			EntityMappingType entityDescriptor,
 			RuntimeModelCreationContext runtimeModelCreationContext) {
 		return new LocalTemporaryTableStrategy(
 				new IdTable( entityDescriptor, basename -> "#" + basename, this ),
+				() -> new TempIdTableExporter( true, this::getTypeName ) {
+					@Override
+					protected String getCreateCommand() {
+						return "create table";
+					}
+				},
 //				// sql-server, at least needed this dropped after use; strange!
-				this::getTypeName,
 				AfterUseAction.DROP,
 				TempTableDdlTransactionHandling.NONE,
 				runtimeModelCreationContext.getSessionFactory()

hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java

@@ -698,8 +698,13 @@ public class DB2Dialect extends Dialect {
 	}
 
 	@Override
-	public boolean supportsGroupByRollup() {
-		return true;
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return GroupBySummarizationRenderingStrategy.FUNCTION;
+	}
+
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.EMPTY_GROUPING;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/dialect/DerbyDialect.java

@@ -766,7 +766,7 @@ public class DerbyDialect extends Dialect {
 			EntityMappingType rootEntityDescriptor,
 			RuntimeModelCreationContext runtimeModelCreationContext) {
 		return new LocalTemporaryTableStrategy(
-				new IdTable( rootEntityDescriptor, basename -> "HT_" + basename, this ),
+				new IdTable( rootEntityDescriptor, basename -> "session.HT_" + basename, this ),
 				() -> new TempIdTableExporter( true, this::getTypeName ) {
 					@Override
 					protected String getCreateCommand() {
@@ -785,7 +785,7 @@ public class DerbyDialect extends Dialect {
 	}
 
 	@Override
-	public boolean supportsGroupByRollup() {
-		return true;
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return GroupBySummarizationRenderingStrategy.FUNCTION;
 	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/Dialect.java

@@ -360,10 +360,6 @@ public abstract class Dialect implements ConversionContext {
 
 		CommonFunctionFactory.aggregates(queryEngine);
 
-		//grouping functions cube() and rollup() supported on some databases
-
-		CommonFunctionFactory.groupings(queryEngine);
-
 		//the ANSI SQL-defined aggregate functions any() and every() are only
 		//supported on one database, but can be emulated using sum() and case,
 		//though there is a more natural mapping on some databases
@@ -2625,14 +2621,21 @@ public abstract class Dialect implements ConversionContext {
 	}
 
 	/**
-	 * Is this dialect known to support ROLLUP functions in the GROUP BY clause.
+	 * The strategy to use for rendering summarizations in the GROUP BY clause.
 	 *
-	 * @return True if this SQL dialect supports ROLLUP functions; false otherwise.
 	 * @since 6.0
 	 */
-	public boolean supportsGroupByRollup() {
-		// return false here, as most databases do not properly support this construct...
-		return false;
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return GroupBySummarizationRenderingStrategy.NONE;
+	}
+
+	/**
+	 * The strategy to use for rendering constants in the GROUP BY clause.
+	 *
+	 * @since 6.0
+	 */
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.CONSTANT_EXPRESSION;
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/dialect/GroupByConstantRenderingStrategy.java

@@ -0,0 +1,35 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.dialect;
+
+/**
+ * Strategies for rendering a constant in a group by.
+ *
+ * @author Christian Beikov
+ */
+public enum GroupByConstantRenderingStrategy {
+	/**
+	 * The strategy for ANSI SQL compliant DBs like e.g. PostgreSQL that renders `()` i.e. the empty grouping.
+	 */
+	EMPTY_GROUPING,
+	/**
+	 * Renders a constant e.g. `'0'`
+	 */
+	CONSTANT,
+	/**
+	 * Renders a constant expression e.g. `'0' || '0'`
+	 */
+	CONSTANT_EXPRESSION,
+	/**
+	 * Renders a subquery e.g. `(select 1)`
+	 */
+	SUBQUERY,
+	/**
+	 * Renders a column reference to a dummy table e.g. `, (select 1 x) dummy` and `dummy.x`
+	 */
+	COLUMN_REFERENCE;
+}

hibernate-core/src/main/java/org/hibernate/dialect/GroupBySummarizationRenderingStrategy.java

@@ -0,0 +1,27 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.dialect;
+
+/**
+ * Strategies for rendering summarization function like rollup and cube in a group by.
+ *
+ * @author Christian Beikov
+ */
+public enum GroupBySummarizationRenderingStrategy {
+	/**
+	 * No support for summarization.
+	 */
+	NONE,
+	/**
+	 * Use the proprietary WITH ROLLUP or WITH CUBE clause.
+	 */
+	CLAUSE,
+	/**
+	 * Use the rollup or cube functions like specified in the SQL standard.
+	 */
+	FUNCTION;
+}

hibernate-core/src/main/java/org/hibernate/dialect/InformixDialect.java

@@ -334,6 +334,11 @@ public class InformixDialect extends Dialect {
 		return "select distinct current timestamp from informix.systables";
 	}
 
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.COLUMN_REFERENCE;
+	}
+
 	@Override
 	public SqmMultiTableMutationStrategy getFallbackSqmMutationStrategy(
 			EntityMappingType rootEntityDescriptor,

hibernate-core/src/main/java/org/hibernate/dialect/IngresDialect.java

@@ -420,4 +420,9 @@ public class IngresDialect extends Dialect {
 		}
 	}
 
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.COLUMN_REFERENCE;
+	}
+
 }

hibernate-core/src/main/java/org/hibernate/dialect/MariaDBDialect.java

@@ -107,6 +107,11 @@ public class MariaDBDialect extends MySQLDialect {
 		return getVersion() >= 1030;
 	}
 
+	@Override
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return GroupBySummarizationRenderingStrategy.CLAUSE;
+	}
+
 	@Override
 	boolean supportsForShare() {
 		//only supported on MySQL

hibernate-core/src/main/java/org/hibernate/dialect/MySQLDialect.java

@@ -922,7 +922,7 @@ public class MySQLDialect extends Dialect {
 	}
 
 	@Override
-	public boolean supportsGroupByRollup() {
-		return true;
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return GroupBySummarizationRenderingStrategy.CLAUSE;
 	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/OracleDialect.java

@@ -30,6 +30,8 @@ import org.hibernate.exception.spi.TemplatedViolatedConstraintNameExtractor;
 import org.hibernate.exception.spi.ViolatedConstraintNameExtractor;
 import org.hibernate.internal.util.JdbcExceptionHelper;
 import org.hibernate.internal.util.StringHelper;
+import org.hibernate.metamodel.mapping.EntityMappingType;
+import org.hibernate.metamodel.spi.RuntimeModelCreationContext;
 import org.hibernate.procedure.internal.StandardCallableStatementSupport;
 import org.hibernate.procedure.spi.CallableStatementSupport;
 import org.hibernate.query.CastType;
@@ -37,6 +39,11 @@ import org.hibernate.query.SemanticException;
 import org.hibernate.query.TemporalUnit;
 import org.hibernate.query.spi.QueryEngine;
 import org.hibernate.query.spi.QueryOptions;
+import org.hibernate.query.sqm.mutation.internal.idtable.AfterUseAction;
+import org.hibernate.query.sqm.mutation.internal.idtable.GlobalTemporaryTableStrategy;
+import org.hibernate.query.sqm.mutation.internal.idtable.IdTable;
+import org.hibernate.query.sqm.mutation.internal.idtable.TempIdTableExporter;
+import org.hibernate.query.sqm.mutation.spi.SqmMultiTableMutationStrategy;
 import org.hibernate.service.ServiceRegistry;
 import org.hibernate.sql.*;
 import org.hibernate.tool.schema.extract.internal.SequenceInformationExtractorOracleDatabaseImpl;
@@ -807,8 +814,13 @@ public class OracleDialect extends Dialect {
 	}
 
 	@Override
-	public boolean supportsGroupByRollup() {
-		return true;
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return GroupBySummarizationRenderingStrategy.FUNCTION;
+	}
+
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.EMPTY_GROUPING;
 	}
 
 	@Override
@@ -826,6 +838,23 @@ public class OracleDialect extends Dialect {
 		return true;
 	}
 
+	@Override
+	public SqmMultiTableMutationStrategy getFallbackSqmMutationStrategy(
+			EntityMappingType rootEntityDescriptor,
+			RuntimeModelCreationContext runtimeModelCreationContext) {
+		return new GlobalTemporaryTableStrategy(
+				new IdTable( rootEntityDescriptor, name -> name.length() > 30 ? name.substring( 0, 30 ) : name, this ),
+				() -> new TempIdTableExporter( false, this::getTypeName ) {
+					@Override
+					protected String getCreateOptions() {
+						return "on commit delete rows";
+					}
+				},
+				AfterUseAction.CLEAN,
+				runtimeModelCreationContext.getSessionFactory()
+		);
+	}
+
 	/**
 	 * For Oracle, the FOR UPDATE clause cannot be applied when using ORDER BY, DISTINCT or views.
 	 *

hibernate-core/src/main/java/org/hibernate/dialect/PostgreSQLDialect.java

@@ -781,8 +781,13 @@ public class PostgreSQLDialect extends Dialect {
 	}
 
 	@Override
-	public boolean supportsGroupByRollup() {
-		return getVersion() >= 950;
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return getVersion() >= 950 ? GroupBySummarizationRenderingStrategy.FUNCTION : GroupBySummarizationRenderingStrategy.NONE;
+	}
+
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return getVersion() >= 950 ? GroupByConstantRenderingStrategy.EMPTY_GROUPING : GroupByConstantRenderingStrategy.SUBQUERY;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/dialect/SQLServerDialect.java

@@ -359,8 +359,8 @@ public class SQLServerDialect extends AbstractTransactSQLDialect {
 	}
 
 	@Override
-	public boolean supportsGroupByRollup() {
-		return true;
+	public GroupBySummarizationRenderingStrategy getGroupBySummarizationRenderingStrategy() {
+		return GroupBySummarizationRenderingStrategy.CLAUSE;
 	}
 
 	@Override
@@ -638,4 +638,9 @@ public class SQLServerDialect extends AbstractTransactSQLDialect {
 		}
 	}
 
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.EMPTY_GROUPING;
+	}
+
 }

hibernate-core/src/main/java/org/hibernate/dialect/SybaseAnywhereDialect.java

@@ -130,4 +130,9 @@ public class SybaseAnywhereDialect extends SybaseDialect {
 		//      by default
 		return TopLimitHandler.INSTANCE;
 	}
+
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.EMPTY_GROUPING;
+	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/TeradataDialect.java

@@ -549,4 +549,9 @@ public class TeradataDialect extends Dialect {
 		//TODO: is this right?!
 		return TopLimitHandler.INSTANCE;
 	}
+
+	@Override
+	public GroupByConstantRenderingStrategy getGroupByConstantRenderingStrategy() {
+		return GroupByConstantRenderingStrategy.EMPTY_GROUPING;
+	}
 }

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

@@ -1431,15 +1431,6 @@ public class CommonFunctionFactory {
 				.register();
 	}
 
-	public static void groupings(QueryEngine queryEngine) {
-		queryEngine.getSqmFunctionRegistry().namedDescriptorBuilder("cube")
-				.setMinArgumentCount(1)
-				.register();
-		queryEngine.getSqmFunctionRegistry().namedDescriptorBuilder("rollup")
-				.setMinArgumentCount(1)
-				.register();
-	}
-
 	public static void aggregates(QueryEngine queryEngine) {
 		queryEngine.getSqmFunctionRegistry().namedDescriptorBuilder("max")
 				.setExactArgumentCount(1)

hibernate-core/src/main/java/org/hibernate/query/hql/internal/SemanticQueryBuilder.java

@@ -119,6 +119,7 @@ import org.hibernate.query.sqm.tree.expression.SqmParameterizedEntityType;
 import org.hibernate.query.sqm.tree.expression.SqmPathEntityType;
 import org.hibernate.query.sqm.tree.expression.SqmPositionalParameter;
 import org.hibernate.query.sqm.tree.expression.SqmStar;
+import org.hibernate.query.sqm.tree.expression.SqmSummarization;
 import org.hibernate.query.sqm.tree.expression.SqmToDuration;
 import org.hibernate.query.sqm.tree.expression.SqmTrimSpecification;
 import org.hibernate.query.sqm.tree.expression.SqmTuple;
@@ -3307,31 +3308,19 @@ public class SemanticQueryBuilder extends HqlParserBaseVisitor implements SqmCre
 
 	@Override
 	public SqmExpression<?> visitCube(HqlParser.CubeContext ctx) {
-		List<SqmTypedNode<?>> args = new ArrayList<>();
-		for ( HqlParser.ExpressionContext arg: ctx.expression() ) {
-			args.add( (SqmExpression<?>) arg.accept( this ) );
-		}
-		//ignore DISTINCT
-		return getFunctionDescriptor("cube").generateSqmExpression(
-				args,
-				resolveExpressableTypeBasic( Integer.class ),
-				creationContext.getQueryEngine(),
-				creationContext.getJpaMetamodel().getTypeConfiguration()
+		return new SqmSummarization<>(
+				SqmSummarization.Kind.CUBE,
+				visitExpressions( ctx.expression() ),
+				creationContext.getNodeBuilder()
 		);
 	}
 
 	@Override
 	public SqmExpression<?> visitRollup(HqlParser.RollupContext ctx) {
-		List<SqmTypedNode<?>> args = new ArrayList<>();
-		for ( HqlParser.ExpressionContext arg: ctx.expression() ) {
-			args.add( (SqmExpression<?>) arg.accept( this ) );
-		}
-		//ignore DISTINCT
-		return getFunctionDescriptor("rollup").generateSqmExpression(
-				args,
-				resolveExpressableTypeBasic( Integer.class ),
-				creationContext.getQueryEngine(),
-				creationContext.getJpaMetamodel().getTypeConfiguration()
+		return new SqmSummarization<>(
+				SqmSummarization.Kind.ROLLUP,
+				visitExpressions( ctx.expression() ),
+				creationContext.getNodeBuilder()
 		);
 	}
 

hibernate-core/src/main/java/org/hibernate/query/sqm/SemanticQueryWalker.java

@@ -49,6 +49,7 @@ import org.hibernate.query.sqm.tree.expression.SqmNamedParameter;
 import org.hibernate.query.sqm.tree.expression.SqmPathEntityType;
 import org.hibernate.query.sqm.tree.expression.SqmPositionalParameter;
 import org.hibernate.query.sqm.tree.expression.SqmRestrictedSubQueryExpression;
+import org.hibernate.query.sqm.tree.expression.SqmSummarization;
 import org.hibernate.query.sqm.tree.expression.SqmToDuration;
 import org.hibernate.query.sqm.tree.expression.SqmTuple;
 import org.hibernate.query.sqm.tree.expression.SqmUnaryOperation;
@@ -205,6 +206,8 @@ public interface SemanticQueryWalker<T> {
 
 	T visitEvery(SqmEvery<?> sqmEvery);
 
+	T visitSummarization(SqmSummarization<?> sqmSummarization);
+
 	T visitPositionalParameterExpression(SqmPositionalParameter<?> expression);
 
 	T visitNamedParameterExpression(SqmNamedParameter<?> expression);

hibernate-core/src/main/java/org/hibernate/query/sqm/internal/SqmTreePrinter.java

@@ -56,6 +56,7 @@ import org.hibernate.query.sqm.tree.expression.SqmPathEntityType;
 import org.hibernate.query.sqm.tree.expression.SqmPositionalParameter;
 import org.hibernate.query.sqm.tree.expression.SqmRestrictedSubQueryExpression;
 import org.hibernate.query.sqm.tree.expression.SqmStar;
+import org.hibernate.query.sqm.tree.expression.SqmSummarization;
 import org.hibernate.query.sqm.tree.expression.SqmToDuration;
 import org.hibernate.query.sqm.tree.expression.SqmTrimSpecification;
 import org.hibernate.query.sqm.tree.expression.SqmTuple;
@@ -935,6 +936,11 @@ public class SqmTreePrinter implements SemanticQueryWalker<Object> {
 		return null;
 	}
 
+	@Override
+	public Object visitSummarization(SqmSummarization<?> sqmSummarization) {
+		return null;
+	}
+
 	@Override
 	public Object visitDynamicInstantiation(SqmDynamicInstantiation sqmDynamicInstantiation) {
 		processStanza(

hibernate-core/src/main/java/org/hibernate/query/sqm/spi/BaseSemanticQueryWalker.java

@@ -51,6 +51,7 @@ import org.hibernate.query.sqm.tree.expression.SqmParameterizedEntityType;
 import org.hibernate.query.sqm.tree.expression.SqmPathEntityType;
 import org.hibernate.query.sqm.tree.expression.SqmPositionalParameter;
 import org.hibernate.query.sqm.tree.expression.SqmRestrictedSubQueryExpression;
+import org.hibernate.query.sqm.tree.expression.SqmSummarization;
 import org.hibernate.query.sqm.tree.expression.SqmToDuration;
 import org.hibernate.query.sqm.tree.expression.SqmTuple;
 import org.hibernate.query.sqm.tree.expression.SqmUnaryOperation;
@@ -633,6 +634,11 @@ public abstract class BaseSemanticQueryWalker implements SemanticQueryWalker<Obj
 		return sqmEvery;
 	}
 
+	@Override
+	public Object visitSummarization(SqmSummarization<?> sqmSummarization) {
+		return sqmSummarization;
+	}
+
 	@Override
 	public Object visitSearchedCaseExpression(SqmCaseSearched<?> expression) {
 		return expression;

hibernate-core/src/main/java/org/hibernate/query/sqm/sql/BaseSqmToSqlAstConverter.java

@@ -108,6 +108,7 @@ import org.hibernate.query.sqm.tree.expression.SqmNamedParameter;
 import org.hibernate.query.sqm.tree.expression.SqmParameter;
 import org.hibernate.query.sqm.tree.expression.SqmPositionalParameter;
 import org.hibernate.query.sqm.tree.expression.SqmStar;
+import org.hibernate.query.sqm.tree.expression.SqmSummarization;
 import org.hibernate.query.sqm.tree.expression.SqmToDuration;
 import org.hibernate.query.sqm.tree.expression.SqmTrimSpecification;
 import org.hibernate.query.sqm.tree.expression.SqmTuple;
@@ -179,6 +180,7 @@ import org.hibernate.sql.ast.tree.expression.QueryLiteral;
 import org.hibernate.sql.ast.tree.expression.SqlSelectionExpression;
 import org.hibernate.sql.ast.tree.expression.SqlTuple;
 import org.hibernate.sql.ast.tree.expression.Star;
+import org.hibernate.sql.ast.tree.expression.Summarization;
 import org.hibernate.sql.ast.tree.expression.TrimSpecification;
 import org.hibernate.sql.ast.tree.expression.UnaryOperation;
 import org.hibernate.sql.ast.tree.from.TableGroup;
@@ -2235,6 +2237,30 @@ public abstract class BaseSqmToSqlAstConverter
 		);
 	}
 
+	@Override
+	public Object visitSummarization(SqmSummarization<?> sqmSummarization) {
+		final List<SqmExpression<?>> groupingExpressions = sqmSummarization.getGroupings();
+		final int size = groupingExpressions.size();
+		final List<Expression> expressions = new ArrayList<>( size );
+		for ( int i = 0; i < size; i++ ) {
+			expressions.add( (Expression) groupingExpressions.get( i ).accept( this ) );
+		}
+		return new Summarization(
+				getSummarizationKind(sqmSummarization.getKind()),
+				expressions
+		);
+	}
+
+	private Summarization.Kind getSummarizationKind(SqmSummarization.Kind kind) {
+		switch ( kind ) {
+			case CUBE:
+				return Summarization.Kind.CUBE;
+			case ROLLUP:
+				return Summarization.Kind.ROLLUP;
+		}
+		throw new UnsupportedOperationException( "Unsupported summarization: " + kind );
+	}
+
 	@Override
 	public Object visitEnumLiteral(SqmEnumLiteral sqmEnumLiteral) {
 		return new QueryLiteral<>(

hibernate-core/src/main/java/org/hibernate/query/sqm/tree/expression/SqmSummarization.java

@@ -0,0 +1,47 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.query.sqm.tree.expression;
+
+import java.util.List;
+
+import org.hibernate.query.sqm.NodeBuilder;
+import org.hibernate.query.sqm.SemanticQueryWalker;
+import org.hibernate.query.sqm.tree.select.SqmSubQuery;
+
+/**
+ * @author Christian Beikov
+ */
+public class SqmSummarization<T> extends AbstractSqmExpression<T> {
+
+	private final Kind kind;
+	private final List<SqmExpression<?>> groupings;
+
+	public SqmSummarization(Kind kind, List<SqmExpression<?>> groupings, NodeBuilder criteriaBuilder) {
+		super( null, criteriaBuilder );
+		this.kind = kind;
+		this.groupings = groupings;
+	}
+
+	public Kind getKind() {
+		return kind;
+	}
+
+	public List<SqmExpression<?>> getGroupings() {
+		return groupings;
+	}
+
+	@Override
+	public <X> X accept(SemanticQueryWalker<X> walker) {
+		return walker.visitSummarization( this );
+	}
+
+	public enum Kind {
+		ROLLUP,
+		CUBE
+	}
+
+}

hibernate-core/src/main/java/org/hibernate/sql/ast/SqlAstWalker.java

@@ -30,6 +30,7 @@ import org.hibernate.sql.ast.tree.expression.SelfRenderingExpression;
 import org.hibernate.sql.ast.tree.expression.SqlSelectionExpression;
 import org.hibernate.sql.ast.tree.expression.SqlTuple;
 import org.hibernate.sql.ast.tree.expression.Star;
+import org.hibernate.sql.ast.tree.expression.Summarization;
 import org.hibernate.sql.ast.tree.expression.TrimSpecification;
 import org.hibernate.sql.ast.tree.expression.UnaryOperation;
 import org.hibernate.sql.ast.tree.from.FromClause;
@@ -106,6 +107,8 @@ public interface SqlAstWalker {
 
 	void visitEvery(Every every);
 
+	void visitSummarization(Summarization every);
+
 	void visitSelfRenderingExpression(SelfRenderingExpression expression);
 
 	void visitSqlSelectionExpression(SqlSelectionExpression expression);

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/AbstractSqlAstWalker.java

@@ -67,6 +67,7 @@ import org.hibernate.sql.ast.tree.expression.SelfRenderingExpression;
 import org.hibernate.sql.ast.tree.expression.SqlSelectionExpression;
 import org.hibernate.sql.ast.tree.expression.SqlTuple;
 import org.hibernate.sql.ast.tree.expression.Star;
+import org.hibernate.sql.ast.tree.expression.Summarization;
 import org.hibernate.sql.ast.tree.expression.TrimSpecification;
 import org.hibernate.sql.ast.tree.expression.UnaryOperation;
 import org.hibernate.sql.ast.tree.from.FromClause;
@@ -369,7 +370,49 @@ public abstract class AbstractSqlAstWalker
 		// We render an empty group instead of literals as some DBs don't support grouping by literals
 		// Note that integer literals, which refer to select item positions, are handled in #visitGroupByClause
 		if ( expression instanceof Literal ) {
-			appendSql( "()" );
+			switch ( dialect.getGroupByConstantRenderingStrategy() ) {
+				case CONSTANT:
+					appendSql( "'0'" );
+					break;
+				case CONSTANT_EXPRESSION:
+					appendSql( "'0' || '0'" );
+					break;
+				case EMPTY_GROUPING:
+					appendSql( "()" );
+					break;
+				case SUBQUERY:
+					appendSql( "(select 1 " );
+					appendSql( dialect.getFromDual() );
+					appendSql( ')' );
+					break;
+				case COLUMN_REFERENCE:
+					// todo (6.0): We need to introduce a dummy from clause item
+//					String fromItem = ", (select 1 x " + dialect.getFromDual() + ") dummy";
+//					sqlBuffer.insert( fromEndIndex, fromItem );
+//					appendSql( "dummy.x" );
+					throw new UnsupportedOperationException( "Column reference strategy is not yet implemented!" );
+			}
+		}
+		else if ( expression instanceof Summarization ) {
+			Summarization summarization = (Summarization) expression;
+			switch ( dialect.getGroupBySummarizationRenderingStrategy() ) {
+				case FUNCTION:
+					appendSql( summarization.getKind().name().toLowerCase() );
+					appendSql( OPEN_PARENTHESIS );
+					renderCommaSeparated( summarization.getGroupings() );
+					appendSql( CLOSE_PARENTHESIS );
+					break;
+				case CLAUSE:
+					renderCommaSeparated( summarization.getGroupings() );
+					appendSql( " with " );
+					appendSql( summarization.getKind().name().toLowerCase() );
+					break;
+				default:
+					// This could theoretically be emulated by rendering all grouping variations of the query and
+					// connect them via union all but that's probably pretty inefficient and would have to happen
+					// on the query spec level
+					throw new UnsupportedOperationException( "Summarization is not supported by DBMS!" );
+			}
 		}
 		else {
 			expression.accept( this );
@@ -497,12 +540,7 @@ public abstract class AbstractSqlAstWalker
 		try {
 			appendSql( "select " );
 
-			String separator = NO_SEPARATOR;
-			for ( Expression expression : expressions ) {
-				appendSql( separator );
-				expression.accept( this );
-				separator = COMA_SEPARATOR;
-			}
+			renderCommaSeparated( expressions );
 			String fromDual = dialect.getFromDual();
 			if ( !fromDual.isEmpty() ) {
 				appendSql( " " );
@@ -985,17 +1023,22 @@ public abstract class AbstractSqlAstWalker
 			appendSql( OPEN_PARENTHESIS );
 		}
 
-		for ( Expression expression : tuple.getExpressions() ) {
-			appendSql( separator );
-			expression.accept( this );
-			separator = COMA_SEPARATOR;
-		}
+		renderCommaSeparated( tuple.getExpressions() );
 
 		if ( isCurrentWhereClause ) {
 			appendSql( CLOSE_PARENTHESIS );
 		}
 	}
 
+	private void renderCommaSeparated(Iterable<? extends Expression> expressions) {
+		String separator = NO_SEPARATOR;
+		for ( Expression expression : expressions ) {
+			appendSql( separator );
+			expression.accept( this );
+			separator = COMA_SEPARATOR;
+		}
+	}
+
 	@Override
 	public void visitCollate(Collate collate) {
 		collate.getExpression().accept( this );
@@ -1366,6 +1409,11 @@ public abstract class AbstractSqlAstWalker
 		every.getSubquery().accept( this );
 	}
 
+	@Override
+	public void visitSummarization(Summarization every) {
+		// nothing to do... handled within #renderGroupByItem
+	}
+
 	@Override
 	public void visitJdbcLiteral(JdbcLiteral jdbcLiteral) {
 		visitLiteral( jdbcLiteral );
@@ -1538,12 +1586,7 @@ public abstract class AbstractSqlAstWalker
 					appendSql( " not" );
 				}
 				appendSql( " in (" );
-				String separator = NO_SEPARATOR;
-				for ( Expression expression : inListPredicate.getListExpressions() ) {
-					appendSql( separator );
-					expression.accept( this );
-					separator = COMA_SEPARATOR;
-				}
+				renderCommaSeparated( inListPredicate.getListExpressions() );
 				appendSql( CLOSE_PARENTHESIS );
 			}
 		}
@@ -1553,12 +1596,7 @@ public abstract class AbstractSqlAstWalker
 				appendSql( " not" );
 			}
 			appendSql( " in (" );
-			String separator = NO_SEPARATOR;
-			for ( Expression expression : inListPredicate.getListExpressions() ) {
-				appendSql( separator );
-				expression.accept( this );
-				separator = COMA_SEPARATOR;
-			}
+			renderCommaSeparated( inListPredicate.getListExpressions() );
 			appendSql( CLOSE_PARENTHESIS );
 		}
 	}

hibernate-core/src/main/java/org/hibernate/sql/ast/tree/expression/Summarization.java

@@ -0,0 +1,49 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.sql.ast.tree.expression;
+
+import java.util.List;
+
+import org.hibernate.metamodel.mapping.MappingModelExpressable;
+import org.hibernate.sql.ast.SqlAstWalker;
+
+/**
+ * @author Christian Beikov
+ */
+public class Summarization implements Expression {
+
+	private final Kind kind;
+	private final List<Expression> groupings;
+
+	public Summarization(Kind kind, List<Expression> groupings) {
+		this.kind = kind;
+		this.groupings = groupings;
+	}
+
+	public Kind getKind() {
+		return kind;
+	}
+
+	public List<Expression> getGroupings() {
+		return groupings;
+	}
+
+	@Override
+	public MappingModelExpressable getExpressionType() {
+		return null;
+	}
+
+	@Override
+	public void accept(SqlAstWalker walker) {
+		walker.visitSummarization( this );
+	}
+
+	public enum Kind {
+		ROLLUP,
+		CUBE
+	}
+}

hibernate-testing/src/main/java/org/hibernate/testing/orm/junit/DialectFeatureChecks.java

@@ -8,6 +8,7 @@ package org.hibernate.testing.orm.junit;
 
 import org.hibernate.dialect.DerbyDialect;
 import org.hibernate.dialect.Dialect;
+import org.hibernate.dialect.GroupBySummarizationRenderingStrategy;
 
 /**
  * Container class for different implementation of the {@link DialectFeatureCheck} interface.
@@ -223,7 +224,7 @@ abstract public class DialectFeatureChecks {
 
 	public static class SupportsGroupByRollup implements DialectFeatureCheck {
 		public boolean apply(Dialect dialect) {
-			return dialect.supportsGroupByRollup();
+			return dialect.getGroupBySummarizationRenderingStrategy() != GroupBySummarizationRenderingStrategy.NONE;
 		}
 	}