[DERBY-2775] DataTypeDescriptor should be immutable so that multiple ValueNode referring to the same DTD do not have unexpected state changes.

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Fix Version/s: 10.4.1.3
• Component/s: Services, SQL
• Assignee: Daniel John Debrunner
• Reporter: Daniel John Debrunner
• Created: 07/Jun/07 15:22
• Updated: 11/Dec/10 00:17

Description

I think that modifying a DTD to change its collation may be pushing the envelope of "bug-free" code. If several ValueNode's all refer to a single DTD then changing the collation of one changes all of them. This is probably not what is required. The setCollation() pattern did copy the existing setNullablity() pattern which I think is probably also wrong and subject to bugs.
Changing DTD to be (logically) immutable would be a much better solution, e.g. DTD.setNullability() returns a new DTD with the nullability set correctly, leaving the old one unmodified. (The method should also have a name change, setXXX() is wrong since it is not setting the state of the object it is called on). (Also such a method can return the same object if the state is unchanged).

Issue Links

• is blocked by: DERBY-2809 Expressions with a parameter can be assigned the incorrect type
• is related to: DERBY-4284 All Columns become Nullable when Using left join
• is related to: DERBY-3310 ASSERT in MergeSort.checkColumnTypes() disallow legal type conversions
• relates to: DERBY-4913 10.3 to 10.5 upgrade fails with ava.io.StreamCorruptedException: java.lang.ClassCastException: org.apache.derby.catalog.types.OldRoutineType incompatible with org.apache.derby.iapi.types.DataTypeDescriptor

Sub-Tasks

• Refactor DataTypeDescriptor and TypeDescriptor to result in cleaner code.: Open