emulation for FETCH ... WITH TIES on Informix

Author: gavinking

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

@@ -23,6 +23,7 @@
 import org.hibernate.sql.ast.tree.from.ValuesTableReference;
 import org.hibernate.sql.ast.tree.insert.ConflictClause;
 import org.hibernate.sql.ast.tree.insert.InsertSelectStatement;
+import org.hibernate.sql.ast.tree.select.QueryGroup;
 import org.hibernate.sql.ast.tree.select.QueryPart;
 import org.hibernate.sql.ast.tree.select.QuerySpec;
 import org.hibernate.sql.ast.tree.select.SelectClause;
@@ -62,11 +63,14 @@ protected void renderSelectExpression(Expression expression) {
 
 	@Override
 	protected void visitSqlSelections(SelectClause selectClause) {
-		if ( supportsSkipFirstClause() ) {
-			renderSkipFirstClause( (QuerySpec) getQueryPartStack().getCurrent() );
-		}
-		else {
-			renderFirstClause( (QuerySpec) getQueryPartStack().getCurrent() );
+		final QuerySpec querySpec = (QuerySpec) getQueryPartStack().getCurrent();
+		if ( isRowsOnlyFetchClauseType( querySpec ) ) {
+			if ( supportsSkipFirstClause() ) {
+				renderSkipFirstClause( querySpec );
+			}
+			else {
+				renderFirstClause( querySpec );
+			}
 		}
 		if ( selectClause.isDistinct() ) {
 			appendSql( "distinct " );
@@ -198,6 +202,32 @@ public void visitValuesTableReference(ValuesTableReference tableReference) {
 		emulateValuesTableReferenceColumnAliasing( tableReference );
 	}
 
+	protected boolean shouldEmulateFetchClause(QueryPart queryPart) {
+		// Check if current query part is already row numbering to avoid infinite recursion
+		return useOffsetFetchClause( queryPart ) && getQueryPartForRowNumbering() != queryPart
+			   && getDialect().supportsWindowFunctions() && !isRowsOnlyFetchClauseType( queryPart );
+	}
+
+	@Override
+	public void visitQueryGroup(QueryGroup queryGroup) {
+		if ( shouldEmulateFetchClause( queryGroup ) ) {
+			emulateFetchOffsetWithWindowFunctions( queryGroup, true );
+		}
+		else {
+			super.visitQueryGroup( queryGroup );
+		}
+	}
+
+	@Override
+	public void visitQuerySpec(QuerySpec querySpec) {
+		if ( shouldEmulateFetchClause( querySpec ) ) {
+			emulateFetchOffsetWithWindowFunctions( querySpec, true );
+		}
+		else {
+			super.visitQuerySpec( querySpec );
+		}
+	}
+
 	private void caseArgument(Expression expression) {
 		// concatenation inside a case must be cast to varchar(255)
 		// or we get a bunch of trailing whitespace

hibernate-core/src/main/java/org/hibernate/dialect/sql/ast/DB2SqlAstTranslator.java

@@ -304,11 +304,14 @@ protected void emulateFetchOffsetWithWindowFunctionsVisitQueryPart(QueryPart que
 		}
 	}
 
+	private boolean shouldEmulateFetch(QueryPart queryPart) {
+		return shouldEmulateFetchClause( queryPart )
+			|| getQueryPartForRowNumbering() != queryPart && !supportsOffsetClause() && hasOffset( queryPart );
+	}
+
 	@Override
 	public void visitQueryGroup(QueryGroup queryGroup) {
-		final boolean emulateFetchClause = shouldEmulateFetchClause( queryGroup );
-		if ( emulateFetchClause ||
-				getQueryPartForRowNumbering() != queryGroup && !supportsOffsetClause() && hasOffset( queryGroup ) ) {
+		if ( shouldEmulateFetch( queryGroup ) ) {
 			emulateFetchOffsetWithWindowFunctions( queryGroup, true );
 		}
 		else {
@@ -318,9 +321,7 @@ public void visitQueryGroup(QueryGroup queryGroup) {
 
 	@Override
 	public void visitQuerySpec(QuerySpec querySpec) {
-		final boolean emulateFetchClause = shouldEmulateFetchClause( querySpec );
-		if ( emulateFetchClause ||
-				getQueryPartForRowNumbering() != querySpec && !supportsOffsetClause() && hasOffset( querySpec ) ) {
+		if ( shouldEmulateFetch( querySpec ) ) {
 			emulateFetchOffsetWithWindowFunctions( querySpec, true );
 		}
 		else {