Gang Wu created ORC-2213:
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Summary: [C++] Allow reading TIMESTAMP type using writer timezone
Key: ORC-2213
URL: https://issues.apache.org/jira/browse/ORC-2213
Project: ORC
Issue Type: Improvement
Components: C++
Reporter: Gang Wu
Assignee: Gang Wu
In old days, ORC only supports *orc::TIMESTAMP* type so it is difficult to
support both *TIMESTAMP_NTZ* and *TIMESTAMP_LTZ* types. The semantics of
{*}orc::{*}{*}TIMESTAMP{*} is equivalent to *TIMESTAMP_NTZ* but with a complex
writer and reader timezone adjustment. In latter versions,
{*}orc::{*}{*}TIMESTAMP_INSTANT{*} has been added to support *TIMESTAMP_LTZ*
type. However, users may not know the difference under the hood and still use
legacy systems to write both *TIMESTAMP_LTZ* and *TIMESTAMP_NTZ* semantics to
the old {*}orc::{*}{*}TIMESTAMP{*} type. When users use *orc::TIMESTAMP* as
*TIMESTAMP_LTZ* values, we should set reader timezone to the writer timezone to
avoid slight value conversion. However, users may not know the writer timezone
in advance and ORC files may have different writer timezone (considering files
are produced by teams in different time zones.) We need an approach to enforce
reader to use writer timezone via explicit configuration.
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