HHH-12856 Reintroduce limitation for legacy OS400

hibernate-core/src/main/java/org/hibernate/dialect/DB2400Dialect.java

@@ -31,6 +31,17 @@ public class DB2400Dialect extends DB2Dialect {
 		return null;
 	}
 
+	@Override
+	public String getLimitString(String sql, int offset, int limit) {
+		if ( offset > 0 ) {
+			throw new UnsupportedOperationException( "query result offset is not supported" );
+		}
+		if ( limit == 0 ) {
+			return sql;
+		}
+		return sql + " fetch first " + limit + " rows only ";
+	}
+
 	@Override
 	public String getForUpdateString() {
 		return " for update with rs";

hibernate-core/src/main/java/org/hibernate/dialect/DB2400V7R3Dialect.java

@@ -44,6 +44,18 @@ public class DB2400V7R3Dialect extends DB2400Dialect {
 				"or sequence_schema = current_schema";
 	}
 
+	@Override
+	@SuppressWarnings("deprecation")
+	public String getLimitString(String sql, int offset, int limit) {
+		if ( offset == 0 ) {
+			return sql + " fetch first " + limit + " rows only";
+		}
+		//nest the main query in an outer select
+		return "select * from ( select inner2_.*, rownumber() over(order by order of inner2_) as rownumber_ from ( "
+				+ sql + " fetch first " + limit + " rows only ) as inner2_ ) as inner1_ where rownumber_ > "
+				+ offset + " order by rownumber_";
+	}
+
 	@Override
 	public IdentityColumnSupport getIdentityColumnSupport() {
 		return new DB2IdentityColumnSupport();