e9145d41f3
### What changes were proposed in this pull request?
It fixes microseconds rebasing from the hybrid calendar (Julian + Gregorian) to Proleptic Gregorian calendar in the function `RebaseDateTime`.`rebaseJulianToGregorianMicros(zoneId: ZoneId, micros: Long): Long` in the case of local timestamp overlapping.
In the case of overlapping, we look ahead of 1 day to determinate which instant we should take - earlier or later zoned timestamp. If our current standard zone and DST offsets are equal to zone offset of the next date, we choose the later timestamp otherwise the earlier one. For example, the local timestamp **1945-11-18 01:30:00.0** can be mapped to two instants (microseconds since 1970-01-01 00:00:00Z): -761211000000000 or -761207400000000. If the first one is passed to `rebaseJulianToGregorianMicros()`, we take the earlier instant in Proleptic Gregorian calendar while rebasing **1945-11-18T01:30+09:00[Asia/Hong_Kong]** otherwise the later one **1945-11-18T01:30+08:00[Asia/Hong_Kong]**.
Note: The fix assumes that only one transition of standard or DST offsets can occur during a day.
### Why are the changes needed?
Current implementation of `rebaseJulianToGregorianMicros()` handles timestamps overlapping only during daylight saving time but overlapping can happen also during transition from one standard time zone to another one. For example in the case of `Asia/Hong_Kong`, the time zone switched from `Japan Standard Time` (UTC+9) to `Hong Kong Time` (UTC+8) on _Sunday, 18 November, 1945 01:59:59 AM_. The changes allow to handle the special case as well.
### Does this PR introduce _any_ user-facing change?
There is no behaviour change for timestamps of CE after 0001-01-01. The PR might affects timestamps of BCE for which the modified `rebaseJulianToGregorianMicros()` is called directly.
### How was this patch tested?
1. By existing tests in `DateTimeUtilsSuite`, `RebaseDateTimeSuite`, `DateFunctionsSuite`, `DateExpressionsSuite` and `TimestampFormatterSuite`.
2. Added new checks to `RebaseDateTimeSuite`.`SPARK-31959: JST -> HKT at Asia/Hong_Kong in 1945`:
```scala
assert(rebaseJulianToGregorianMicros(hkZid, rebasedEarlierMicros) === earlierMicros)
assert(rebaseJulianToGregorianMicros(hkZid, rebasedLaterMicros) === laterMicros)
```
3. Regenerated `julian-gregorian-rebase-micros.json` with the step of 30 minutes, and got the same JSON file. The JSON file isn't affected because previously it was generated with the step of 1 week. And the spike in diffs/switch points during 1 hour of timestamp overlapping wasn't detected.
Closes #28816 from MaxGekk/fix-overlap-julian-2-grep.
Authored-by: Max Gekk <max.gekk@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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| .. | ||
| catalyst | ||
| core | ||
| hive | ||
| hive-thriftserver | ||
| create-docs.sh | ||
| gen-sql-api-docs.py | ||
| gen-sql-config-docs.py | ||
| gen-sql-functions-docs.py | ||
| mkdocs.yml | ||
| README.md | ||
Spark SQL
This module provides support for executing relational queries expressed in either SQL or the DataFrame/Dataset API.
Spark SQL is broken up into four subprojects:
- Catalyst (sql/catalyst) - An implementation-agnostic framework for manipulating trees of relational operators and expressions.
- Execution (sql/core) - A query planner / execution engine for translating Catalyst's logical query plans into Spark RDDs. This component also includes a new public interface, SQLContext, that allows users to execute SQL or LINQ statements against existing RDDs and Parquet files.
- Hive Support (sql/hive) - Includes extensions that allow users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allow users to run queries that include Hive UDFs, UDAFs, and UDTFs.
- HiveServer and CLI support (sql/hive-thriftserver) - Includes support for the SQL CLI (bin/spark-sql) and a HiveServer2 (for JDBC/ODBC) compatible server.
Running ./sql/create-docs.sh generates SQL documentation for built-in functions under sql/site, and SQL configuration documentation that gets included as part of configuration.md in the main docs directory.