[C++][ORC] Fix timestamp type mapping between orc and arrow

[wgtmac]

Describe the enhancement requested

Background: There was an effort to fix inconsistent timestamp types across different SQL-on-Hadoop engines: https://docs.google.com/document/d/1gNRww9mZJcHvUDCXklzjFEQGpefsuR_akCDfWsdE35Q

In the Apache Orc, two timestamp types are provided:

• TIMESTAMP: timestamp type without timezone, timestamp value is stored in the writer timezone .
• TIMESTAMP_INSTANT: timestamp type with local timezone, timestamp value is stored in the UTC timezone.

arrow::TimestampType has an optional timezone field: https://github.com/apache/arrow/blob/main/cpp/src/arrow/type.h#L1385

• If timezone is provided, values are normalized in UTC.
• If timezone is missing, values can be in any timezone.

Therefore, the type mapping should be as below:

• orc::TIMESTAMP <=> arrow::TimestampType w/o timezone
• orc::TIMESTAMP_INSTANT <=> arrow::TimestampType w/ timezone

Component(s)

C++