gengliangwang opened a new pull request #32802:
URL: https://github.com/apache/spark/pull/32802
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### What changes were proposed in this pull request?
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Extend Catalyst's type system by a new type that conforms to the SQL
standard (see SQL:2016, section 4.6.2): TimestampNTZType represents the
timestamp without time zone type
### Why are the changes needed?
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Spark SQL today supports the TIMESTAMP data type. However the semantics
provided actually match TIMESTAMP WITH LOCAL TIMEZONE as defined by Oracle.
Timestamps embedded in a SQL query or passed through JDBC are presumed to be in
session local timezone and cast to UTC before being processed.
These are desirable semantics in many cases, such as when dealing with
calendars.
In many (more) other cases, such as when dealing with log files it is
desirable that the provided timestamps not be altered.
SQL users expect that they can model either behavior and do so by using
TIMESTAMP WITHOUT TIME ZONE for time zone insensitive data and TIMESTAMP WITH
LOCAL TIME ZONE for time zone sensitive data.
Most traditional RDBMS map TIMESTAMP to TIMESTAMP WITHOUT TIME ZONE and will
be surprised to see TIMESTAMP WITH LOCAL TIME ZONE, a feature that does not
exist in the standard.
In this new feature, we will introduce TIMESTAMP WITH LOCAL TIMEZONE to
describe the existing timestamp type and add TIMESTAMP WITHOUT TIME ZONE for
standard semantic.
Using these two types will provide clarity.
This is a starting PR. See more details in
https://issues.apache.org/jira/browse/SPARK-35662
### Does this PR introduce _any_ user-facing change?
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Yes, a new data type for Timestamp without time zone type. It is still in
development.
### How was this patch tested?
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Unit test
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