Ingres 9.2 Migration Guide - Actian

Considerations for Ingres 6.4Application PreparationAfter successfully creating databases and applications in the new Ingresdevelopment installation, you should check for the following additionalapplication issues.• Semantics change in the UPDATE…FROM statement• Decimal constant semantics change• Greater sensitivity to BYREF errors• Journaling on by default• Greater sensitivity to arithmetic errors• 4GL TABLE_KEY type conversions• User-defined data type changesUPDATE . . . FROM Semantics ChangeIn Ingres 6.4/05 and earlier, the “ambiguous replace” test allowed an updateusing the UPDATE…FROM statement if each target row was being updated withan unambiguous value. Ingres 6.4/06 and higher releases test for multipleFROM rows and generate an ambiguous replace error message even if all theFROM rows generate the same replacement value.For example, Ingres 6.4/05 and earlier allowed the following update:UPDATE table_1FROM table_2SET column_3 = 3;even though there is no WHERE qualification joining the tables, since thereplacement value was non-ambiguous. In later releases, an “ambiguousreplace” error message displays.The recommended approach for this semantics change is to review allapplications for ambiguous updates and change them to use EXISTS or IN,instead of a join. If this is not feasible, the original UPDATE . . . FROM handlingcan be restored by setting the DBMS parameter “ambig_replace_64compat” toON in Configuration-By-Forms.90 Migration Guide