HHH-3356 Support for normal and lateral subquery in from clause

Author: beikov

documentation/src/main/asciidoc/userguide/chapters/query/hql/QueryLanguage.adoc

@@ -1470,6 +1470,21 @@ This behavior may be slightly adjusted using the `@Polymorphism` annotation.
 
 See <<chapters/domain/inheritance.adoc#entity-inheritance-polymorphism>> for more.
 
+[[hql-derived-root]]
+==== Derived root
+
+As of Hibernate 6.1, HQL allows to declare derived roots, based on a sub query in the `from` clause.
+
+[[hql-derived-root-example]]
+====
+[source, JAVA, indent=0]
+----
+include::{sourcedir}/HQLTest.java[tags=hql-derived-root-example, indent=0]
+----
+====
+
+This can be used to split up more complicated queries into smaller parts.
+
 [[hql-join]]
 === Declaring joined entities
 
@@ -1626,6 +1641,31 @@ This allows the attribute `cardNumber` declared by the subtype `CreditCardPaymen
 
 See <<hql-treat-type>> for more information about `treat()`.
 
+[[hql-join-derived]]
+==== Join subquery
+
+As of Hibernate 6.1, HQL allows against to join sub queries.
+
+[[hql-derived-join-example]]
+====
+[source, JAVA, indent=0]
+----
+include::{sourcedir}/HQLTest.java[tags=hql-derived-join-example, indent=0]
+----
+====
+
+This is very similar to defining a <<hql-derived-root,derived root>>, but the particular interesting part here,
+is the use of the `lateral` keyword, which allows to refer to previous from clause nodes within the subquery.
+
+This is particularly useful for computing top-N elements of multiple groups.
+
+[NOTE]
+====
+Most databases support lateral natively, but for certain databases it is necessary to emulate this feature.
+Beware that the emulation is neither very efficient, nor does it support all possible query shapes,
+so be sure to test such queries against your desired target database.
+====
+
 [[hql-implicit-join]]
 ==== Implicit joins (path expressions)
 

documentation/src/main/asciidoc/userguide/chapters/query/hql/extras/statement_select_bnf.txt

@@ -13,3 +13,20 @@ query
 
 queryOrder
 	: orderByClause limitClause? offsetClause? fetchClause?
+
+fromClause
+	: FROM entityWithJoins (COMMA entityWithJoins)*
+
+entityWithJoins
+	: fromRoot (join | crossJoin | jpaCollectionJoin)*
+
+fromRoot
+	: entityName variable?
+	| LATERAL? LEFT_PAREN subquery RIGHT_PAREN variable?
+
+join
+	: joinType JOIN FETCH? joinTarget joinRestriction?
+
+joinTarget
+	: path variable?
+	| LATERAL? LEFT_PAREN subquery RIGHT_PAREN variable?

documentation/src/test/java/org/hibernate/userguide/hql/HQLTest.java

@@ -51,6 +51,7 @@
 import org.hibernate.testing.SkipForDialect;
 import org.hibernate.testing.DialectChecks;
 import org.hibernate.testing.RequiresDialectFeature;
+import org.hibernate.testing.orm.junit.DialectFeatureChecks;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -3043,4 +3044,47 @@ public void test_hql_read_only_entities_native_example() {
 			//end::hql-read-only-entities-native-example[]
 		});
 	}
+
+	@Test
+	public void test_hql_derived_root_example() {
+
+		doInJPA(this::entityManagerFactory, entityManager -> {
+			//tag::hql-derived-root-example[]
+			List<Tuple> calls = entityManager.createQuery(
+							"select d.owner, d.payed " +
+									"from (" +
+									"  select p.person as owner, c.payment is not null as payed " +
+									"  from Call c " +
+									"  join c.phone p " +
+									"  where p.number = :phoneNumber) d",
+							Tuple.class)
+					.setParameter("phoneNumber", "123-456-7890")
+					.getResultList();
+			//end::hql-derived-root-example[]
+		});
+	}
+
+	@Test
+	@SkipForDialect(value = TiDBDialect.class, comment = "TiDB db does not support subqueries for ON condition")
+	@RequiresDialectFeature(DialectChecks.SupportsOrderByInCorrelatedSubquery.class)
+	public void test_hql_derived_join_example() {
+
+		doInJPA(this::entityManagerFactory, entityManager -> {
+			//tag::hql-derived-join-example[]
+			List<Tuple> calls = entityManager.createQuery(
+							"select longest.duration " +
+									"from Phone p " +
+									"left join lateral (" +
+									"  select c.duration as duration " +
+									"  from p.calls c" +
+									"  order by c.duration desc" +
+									"  limit 1 " +
+									"  ) longest " +
+									"where p.number = :phoneNumber",
+							Tuple.class)
+					.setParameter("phoneNumber", "123-456-7890")
+					.getResultList();
+			//end::hql-derived-join-example[]
+		});
+	}
 }

hibernate-core/src/main/antlr/org/hibernate/grammars/hql/HqlLexer.g4

@@ -207,6 +207,7 @@ IS					: [iI] [sS];
 JOIN				: [jJ] [oO] [iI] [nN];
 KEY					: [kK] [eE] [yY];
 LAST				: [lL] [aA] [sS] [tT];
+LATERAL				: [lL] [aA] [tT] [eE] [rR] [aA] [lL];
 LEADING				: [lL] [eE] [aA] [dD] [iI] [nN] [gG];
 LEFT				: [lL] [eE] [fF] [tT];
 LIKE				: [lL] [iI] [kK] [eE];

hibernate-core/src/main/antlr/org/hibernate/grammars/hql/HqlParser.g4

@@ -169,14 +169,15 @@ fromClause
  * The declaration of a root entity in 'from' clause, along with its joins
  */
 entityWithJoins
-	: rootEntity (join | crossJoin | jpaCollectionJoin)*
+	: fromRoot (join | crossJoin | jpaCollectionJoin)*
 	;
 
 /**
  * A root entity declaration in the 'from' clause, with optional identification variable
  */
-rootEntity
-	: entityName variable?
+fromRoot
+	: entityName variable?									# RootEntity
+	| LATERAL? LEFT_PAREN subquery RIGHT_PAREN variable?	# RootSubquery
 	;
 
 /**
@@ -212,7 +213,7 @@ jpaCollectionJoin
  * A 'join', with an optional 'on' or 'with' clause
  */
 join
-	: joinType JOIN FETCH? joinPath joinRestriction?
+	: joinType JOIN FETCH? joinTarget joinRestriction?
 	;
 
 /**
@@ -226,8 +227,9 @@ joinType
 /**
  * The joined path, with an optional identification variable
  */
-joinPath
-	: path variable?
+joinTarget
+	: path variable?										#JoinPath
+	| LATERAL? LEFT_PAREN subquery RIGHT_PAREN variable?	#JoinSubquery
 	;
 
 /**

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

@@ -1081,7 +1081,8 @@ public boolean supportsValuesListForInsert() {
 
 	@Override
 	public boolean supportsOrderByInSubquery() {
-		return false;
+		// Seems to work, though I don't know as of which version
+		return true;
 	}
 
 	@Override

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

@@ -577,7 +577,8 @@ public boolean supportsTupleDistinctCounts() {
 
 	@Override
 	public boolean supportsOrderByInSubquery() {
-		return false;
+		// As of version 10.5 Derby supports OFFSET and FETCH as well as ORDER BY in subqueries
+		return getVersion().isSameOrAfter( 10, 5 );
 	}
 
 	@Override

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

@@ -31,6 +31,8 @@
  */
 public class HANASqlAstTranslator<T extends JdbcOperation> extends AbstractSqlAstTranslator<T> {
 
+	private boolean inLateral;
+
 	public HANASqlAstTranslator(SessionFactoryImplementor sessionFactory, Statement statement) {
 		super( sessionFactory, statement );
 	}
@@ -64,7 +66,20 @@ public void visitQuerySpec(QuerySpec querySpec) {
 
 	@Override
 	public void visitQueryPartTableReference(QueryPartTableReference tableReference) {
-		emulateQueryPartTableReferenceColumnAliasing( tableReference );
+		if ( tableReference.isLateral() && !inLateral ) {
+			inLateral = true;
+			emulateQueryPartTableReferenceColumnAliasing( tableReference );
+			inLateral = false;
+		}
+		else {
+			emulateQueryPartTableReferenceColumnAliasing( tableReference );
+		}
+	}
+
+	@Override
+	protected SqlAstNodeRenderingMode getParameterRenderingMode() {
+		// HANA does not support parameters in lateral sub queries for some reason, so inline all the parameters in this case
+		return inLateral ? SqlAstNodeRenderingMode.INLINE_ALL_PARAMETERS : super.getParameterRenderingMode();
 	}
 
 	@Override

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

@@ -10,6 +10,8 @@
 import java.util.function.Consumer;
 
 import org.hibernate.engine.spi.SessionFactoryImplementor;
+import org.hibernate.metamodel.mapping.JdbcMapping;
+import org.hibernate.metamodel.mapping.JdbcMappingContainer;
 import org.hibernate.query.sqm.BinaryArithmeticOperator;
 import org.hibernate.query.sqm.ComparisonOperator;
 import org.hibernate.sql.ast.SqlAstNodeRenderingMode;
@@ -213,10 +215,15 @@ protected void renderSelectTupleComparison(
 	}
 
 	protected void renderComparison(Expression lhs, ComparisonOperator operator, Expression rhs) {
+		final JdbcMappingContainer lhsExpressionType = lhs.getExpressionType();
+		if ( lhsExpressionType == null ) {
+			renderComparisonStandard( lhs, operator, rhs );
+			return;
+		}
 		switch ( operator ) {
 			case DISTINCT_FROM:
 			case NOT_DISTINCT_FROM:
-				if ( lhs.getExpressionType().getJdbcMappings().get( 0 ).getJdbcType() instanceof ArrayJdbcType ) {
+				if ( lhsExpressionType.getJdbcMappings().get( 0 ).getJdbcType() instanceof ArrayJdbcType ) {
 					// HSQL implements distinct from semantics for arrays
 					lhs.accept( this );
 					appendSql( operator == ComparisonOperator.DISTINCT_FROM ? "<>" : "=" );

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

@@ -132,6 +132,17 @@ protected boolean supportsRowValueConstructorSyntaxInQuantifiedPredicates() {
 		return false;
 	}
 
+	@Override
+	protected boolean supportsIntersect() {
+		return getDialect().getVersion().isSameOrAfter( 10, 3 );
+	}
+
+	@Override
+	protected boolean supportsDistinctFromPredicate() {
+		// It supports a proprietary operator
+		return true;
+	}
+
 	private boolean supportsWindowFunctions() {
 		return getDialect().getVersion().isSameOrAfter( 10, 2 );
 	}

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

@@ -149,6 +149,17 @@ protected boolean supportsRowValueConstructorSyntaxInQuantifiedPredicates() {
 		return false;
 	}
 
+	@Override
+	protected boolean supportsIntersect() {
+		return false;
+	}
+
+	@Override
+	protected boolean supportsDistinctFromPredicate() {
+		// It supports a proprietary operator
+		return true;
+	}
+
 	@Override
 	protected String getFromDual() {
 		return " from dual";

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

@@ -11,6 +11,7 @@
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.internal.util.collections.Stack;
 import org.hibernate.metamodel.mapping.JdbcMapping;
+import org.hibernate.metamodel.mapping.JdbcMappingContainer;
 import org.hibernate.query.sqm.BinaryArithmeticOperator;
 import org.hibernate.query.sqm.ComparisonOperator;
 import org.hibernate.query.sqm.FetchClauseType;
@@ -354,12 +355,12 @@ public void visitOver(Over<?> over) {
 
 	@Override
 	protected void renderComparison(Expression lhs, ComparisonOperator operator, Expression rhs) {
-		if ( lhs.getExpressionType() == null ) {
+		final JdbcMappingContainer lhsExpressionType = lhs.getExpressionType();
+		if ( lhsExpressionType == null ) {
 			renderComparisonEmulateDecode( lhs, operator, rhs );
 			return;
 		}
-		final JdbcMapping lhsMapping = lhs.getExpressionType().getJdbcMappings().get( 0 );
-		switch ( lhsMapping.getJdbcType().getJdbcTypeCode() ) {
+		switch ( lhsExpressionType.getJdbcMappings().get( 0 ).getJdbcType().getJdbcTypeCode() ) {
 			case SqlTypes.SQLXML:
 				// In Oracle, XMLTYPE is not "comparable", so we have to use the xmldiff function for this purpose
 				switch ( operator ) {

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

@@ -15,6 +15,8 @@
 import org.hibernate.sql.ast.tree.expression.Expression;
 import org.hibernate.sql.ast.tree.expression.Literal;
 import org.hibernate.sql.ast.tree.expression.Summarization;
+import org.hibernate.sql.ast.tree.from.QueryPartTableReference;
+import org.hibernate.sql.ast.tree.from.ValuesTableReference;
 import org.hibernate.sql.ast.tree.predicate.BooleanExpressionPredicate;
 import org.hibernate.sql.ast.tree.select.QueryGroup;
 import org.hibernate.sql.ast.tree.select.QueryPart;
@@ -76,6 +78,16 @@ public void visitQuerySpec(QuerySpec querySpec) {
 		}
 	}
 
+	@Override
+	public void visitValuesTableReference(ValuesTableReference tableReference) {
+		emulateValuesTableReferenceColumnAliasing( tableReference );
+	}
+
+	@Override
+	public void visitQueryPartTableReference(QueryPartTableReference tableReference) {
+		emulateQueryPartTableReferenceColumnAliasing( tableReference );
+	}
+
 	@Override
 	public void visitOffsetFetchClause(QueryPart queryPart) {
 		if ( !isRowNumberingCurrentQueryPart() ) {