HHH-19704 Added dialect enhancement for check if dialect supports listAgg(). Minor refactoring of orderedSet/listagg logic.

Author: Mike Mannion

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

@@ -3676,6 +3676,19 @@ public Set<String> getKeywords() {
 		return sqlKeywords;
 	}
 
+	/**
+	 * Whether this Dialect supports the LISTAGG ordered-set aggregate (including its extensions).
+	 * <p>
+	 * This is used by {@code org.hibernate.sql.Template} to recognize LISTAGG extension soft keywords
+	 * like OVERFLOW/TRUNCATE/etc. Default is {@code true} to preserve historical behavior of Template
+	 * scanning regardless of dialect.
+	 *
+	 * @since 7.1
+	 */
+	public boolean supportsListagg() {
+		return true;
+	}
+
 	/**
 	 * The {@link IdentifierHelper} indicated by this dialect for handling identifier conversions.
 	 * Returning {@code null} is allowed and indicates that Hibernate should fall back to building

hibernate-core/src/main/java/org/hibernate/sql/Template.java

@@ -247,18 +247,6 @@ else if ( quotedIdentifier && dialect.closeQuote()==token.charAt(0) ) {
 			final boolean isQuoted =
 					quoted || quotedIdentifier || isQuoteCharacter;
 
-			// If we're in the post-args region of an ordered-set aggregate, and this
-			// token is a substantive identifier that's not allowed, end the special handling
-			if ( !isQuoted && !isWhitespace && afterOrderedSetArgs && isUnqualifiedIdentifier( token ) ) {
-				final boolean allowedHere = inListaggExtension
-					? LISTAGG_EXTENSION_KEYWORDS.contains( lcToken )
-					: "within".equals( lcToken );
-				if ( !allowedHere ) {
-					afterOrderedSetArgs = false;
-					inListaggExtension = false;
-				}
-			}
-
 			if ( isQuoted || isWhitespace ) {
 				processedToken = token;
 			}
@@ -334,17 +322,6 @@ else if ( isCurrent( lcToken, nextToken, sql, symbols, tokens ) ) {
 			else if ( isBoolean( lcToken ) ) {
 				processedToken = dialect.toBooleanValueString( parseBoolean( token ) );
 			}
-			// Handle ordered-set/LISTAGG post-argument soft keywords (allowed tokens only)
-			else if ( afterOrderedSetArgs && (inListaggExtension
-				? LISTAGG_EXTENSION_KEYWORDS.contains( lcToken )
-				: "within".equals( lcToken )) ) {
-				processedToken = token;
-				if ( "group".equals( lcToken ) ) {
-					// end special handling after GROUP (inclusive)
-					afterOrderedSetArgs = false;
-					inListaggExtension = false;
-				}
-			}
 			else if ( isFunctionCall( nextToken, sql, symbols, tokens ) ) {
 				if ( FUNCTION_WITH_FROM_KEYWORDS.contains( lcToken ) ) {
 					inExtractOrTrim = true;
@@ -359,9 +336,24 @@ else if ( isFunctionCall( nextToken, sql, symbols, tokens ) ) {
 				}
 				processedToken = token;
 			}
+			else if ( afterOrderedSetArgs && (inListaggExtension
+					? ( LISTAGG_EXTENSION_KEYWORDS.contains( lcToken ) && dialect.supportsListagg() )
+					: "within".equals( lcToken )) ) {
+				if ( "group".equals( lcToken ) ) {
+					// end special handling after GROUP (inclusive)
+					afterOrderedSetArgs = false;
+					inListaggExtension = false;
+				}
+				processedToken = token;
+			}
 			else if ( isAliasableIdentifier( token, lcToken, nextToken,
 							sql, symbols, tokens, wasAfterCurrent,
 							dialect, typeConfiguration ) ) {
+				// Any aliasable identifier here cannot be one of the soft keywords allowed in the
+				// ordered-set/LISTAGG post-args region. We've left that region so must end special handling.
+				// (It's irrelevant at this point whether the dialect supports ordered-set/LISTAGG.)
+				afterOrderedSetArgs = false;
+				inListaggExtension = false;
 				processedToken = alias + '.' +  dialect.quote(token);
 			}
 			else {

hibernate-core/src/test/java/org/hibernate/orm/test/sql/TemplateListaggDialectSupportTest.java

@@ -0,0 +1,62 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.sql;
+
+import org.hibernate.dialect.Dialect;
+import org.hibernate.sql.Template;
+import org.hibernate.type.spi.TypeConfiguration;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * Tests that LISTAGG extension soft keywords are only treated specially
+ * when the Dialect reports support for LISTAGG.
+ */
+public class TemplateListaggDialectSupportTest {
+
+	private static final TypeConfiguration TYPE_CONFIGURATION = new TypeConfiguration();
+
+	static class NoListaggDialect extends Dialect {
+		@Override
+		public boolean supportsListagg() {
+			return false;
+		}
+	}
+
+	static class SupportsListaggDialect extends Dialect {
+		@Override
+		public boolean supportsListagg() {
+			return true;
+		}
+	}
+
+	@Test
+	public void listaggExtensionsAllowedWhenSupported() {
+		final Dialect dialect = new SupportsListaggDialect();
+		final String sql = "SELECT LISTAGG(employee_name, ', ') ON OVERFLOW TRUNCATE WITH COUNT WITHIN GROUP (ORDER BY hire_date) FROM employees";
+		final String rendered = Template.renderWhereStringTemplate(sql, dialect, TYPE_CONFIGURATION);
+		final String expected = "SELECT LISTAGG({@}.employee_name, ', ') ON OVERFLOW TRUNCATE WITH COUNT WITHIN GROUP (ORDER BY {@}.hire_date) FROM employees";
+		assertEquals(expected, rendered);
+	}
+
+	@Test
+	public void listaggExtensionsDisallowedWhenNotSupported() {
+		final Dialect dialect = new NoListaggDialect();
+		final String sql = "SELECT LISTAGG(employee_name, ', ') ON OVERFLOW TRUNCATE WITH COUNT WITHIN GROUP (ORDER BY hire_date) FROM employees";
+		final String rendered = Template.renderWhereStringTemplate(sql, dialect, TYPE_CONFIGURATION);
+		final String expected = "SELECT LISTAGG({@}.employee_name, ', ') ON {@}.OVERFLOW {@}.TRUNCATE WITH {@}.COUNT WITHIN GROUP (ORDER BY {@}.hire_date) FROM employees";
+		assertEquals(expected, rendered);
+	}
+
+	@Test
+	public void listaggErrorExtensionDisallowedWhenNotSupported() {
+		final Dialect dialect = new NoListaggDialect();
+		final String sql = "SELECT LISTAGG(employee_name, ', ') ON OVERFLOW ERROR WITHIN GROUP (ORDER BY hire_date) FROM employees";
+		final String rendered = Template.renderWhereStringTemplate(sql, dialect, TYPE_CONFIGURATION);
+		final String expected = "SELECT LISTAGG({@}.employee_name, ', ') ON {@}.OVERFLOW {@}.ERROR WITHIN GROUP (ORDER BY {@}.hire_date) FROM employees";
+		assertEquals(expected, rendered);
+	}
+}