Don't render distinct from predicate on SQL Server versions that don't support it

Author: beikov

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/SQLServerLegacySqlAstTranslator.java

@@ -492,10 +492,28 @@ protected void renderComparison(Expression lhs, ComparisonOperator operator, Exp
 				&& lhsExpressionType.getSingleJdbcMapping().getJdbcType().getDdlTypeCode() == SqlTypes.SQLXML ) {
 			// In SQL Server, XMLTYPE is not "comparable", so we have to cast the two parts to varchar for this purpose
 			switch ( operator ) {
+				case DISTINCT_FROM:
+					if ( !supportsDistinctFromPredicate() ) {
+						appendSql( "not " );
+					}
+				case NOT_DISTINCT_FROM: {
+					if ( !supportsDistinctFromPredicate() ) {
+						appendSql( "exists (select cast(" );
+						getClauseStack().push( Clause.SELECT );
+						visitSqlSelectExpression( lhs );
+						appendSql( " as nvarchar(max))" );
+						appendSql( getFromDualForSelectOnly() );
+						appendSql( " intersect select cast(" );
+						visitSqlSelectExpression( rhs );
+						appendSql( " as nvarchar(max))" );
+						appendSql( getFromDualForSelectOnly() );
+						getClauseStack().pop();
+						appendSql( CLOSE_PARENTHESIS );
+						return;
+					}
+				}
 				case EQUAL:
-				case NOT_DISTINCT_FROM:
 				case NOT_EQUAL:
-				case DISTINCT_FROM:
 					appendSql( "cast(" );
 					lhs.accept( this );
 					appendSql( " as nvarchar(max))" );
@@ -509,7 +527,17 @@ protected void renderComparison(Expression lhs, ComparisonOperator operator, Exp
 					break;
 			}
 		}
-		renderComparisonEmulateIntersect( lhs, operator, rhs );
+		if ( supportsDistinctFromPredicate() ) {
+			renderComparisonStandard( lhs, operator, rhs );
+		}
+		else {
+			renderComparisonEmulateIntersect( lhs, operator, rhs );
+		}
+	}
+
+	@Override
+	protected boolean supportsDistinctFromPredicate() {
+		return getDialect().getVersion().isSameOrAfter( 16 );
 	}
 
 	@Override

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

@@ -463,10 +463,28 @@ protected void renderComparison(Expression lhs, ComparisonOperator operator, Exp
 				&& lhsExpressionType.getSingleJdbcMapping().getJdbcType().getDdlTypeCode() == SqlTypes.SQLXML ) {
 			// In SQL Server, XMLTYPE is not "comparable", so we have to cast the two parts to varchar for this purpose
 			switch ( operator ) {
+				case DISTINCT_FROM:
+					if ( !supportsDistinctFromPredicate() ) {
+						appendSql( "not " );
+					}
+				case NOT_DISTINCT_FROM: {
+					if ( !supportsDistinctFromPredicate() ) {
+						appendSql( "exists (select cast(" );
+						getClauseStack().push( Clause.SELECT );
+						visitSqlSelectExpression( lhs );
+						appendSql( " as nvarchar(max))" );
+						appendSql( getFromDualForSelectOnly() );
+						appendSql( " intersect select cast(" );
+						visitSqlSelectExpression( rhs );
+						appendSql( " as nvarchar(max))" );
+						appendSql( getFromDualForSelectOnly() );
+						getClauseStack().pop();
+						appendSql( CLOSE_PARENTHESIS );
+						return;
+					}
+				}
 				case EQUAL:
-				case NOT_DISTINCT_FROM:
 				case NOT_EQUAL:
-				case DISTINCT_FROM:
 					appendSql( "cast(" );
 					lhs.accept( this );
 					appendSql( " as nvarchar(max))" );
@@ -480,7 +498,17 @@ protected void renderComparison(Expression lhs, ComparisonOperator operator, Exp
 					break;
 			}
 		}
-		renderComparisonEmulateIntersect( lhs, operator, rhs );
+		if ( supportsDistinctFromPredicate() ) {
+			renderComparisonStandard( lhs, operator, rhs );
+		}
+		else {
+			renderComparisonEmulateIntersect( lhs, operator, rhs );
+		}
+	}
+
+	@Override
+	protected boolean supportsDistinctFromPredicate() {
+		return getDialect().getVersion().isSameOrAfter( 16 );
 	}
 
 	@Override