[format] For backward compatibility, new unit fields must have default values matching previous implied unit

[asfimport]

Flatbuffer "defaults the default value" to 0. Which means we interpret previously serialized Flatbuf has having the first element of the enum. In particular Date and Time unit fields end up being read as DateUnit.DAY and TimeUnit.SECOND when the previous implied unit was MILLISECOND for both.

Reporter: Julien Le Dem / @julienledem
Assignee: Julien Le Dem / @julienledem

Related issues:

• Arrow 0.3 release (blocks)
• [JAVA] Introduction of new types has shifted Enumerations (relates to)

PRs and other links:

• PR

_{Note: This issue was originally created as ARROW-887. Please see the migration documentation for further details.}

[asfimport]

Julien Le Dem / @julienledem:
PR: #592

[asfimport]

Julien Le Dem / @julienledem:
Issue resolved by pull request 592
#592