[SPARK-31672][SQL] Fix loading of timestamps before 1582-10-15 from dictionary encoded Parquet columns #28489
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@cloud-fan @HyukjinKwon Please, review this PR. |
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Test build #122474 has finished for PR 28489 at commit
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Test build #122476 has finished for PR 28489 at commit
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LGTM, merging to master/3.0! |
cloud-fan
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May 11, 2020
…ictionary encoded Parquet columns
Modified the `decodeDictionaryIds()` method of `VectorizedColumnReader` to handle especially `TimestampType` when the passed parameter `rebaseDateTime` is true. In that case, decoded milliseconds/microseconds are rebased from the hybrid calendar to Proleptic Gregorian calendar using `RebaseDateTime`.`rebaseJulianToGregorianMicros()`.
This fixes the bug of loading timestamps before the cutover day from dictionary encoded column in parquet files. The code below forces dictionary encoding:
```scala
spark.conf.set("spark.sql.legacy.parquet.rebaseDateTimeInWrite.enabled", true)
scala> spark.conf.set("spark.sql.parquet.outputTimestampType", "TIMESTAMP_MICROS")
scala>
Seq.tabulate(8)(_ => "1001-01-01 01:02:03.123").toDF("tsS")
.select($"tsS".cast("timestamp").as("ts")).repartition(1)
.write
.option("parquet.enable.dictionary", true)
.parquet(path)
```
Load the dates back:
```scala
scala> spark.read.parquet(path).show(false)
+-----------------------+
|ts |
+-----------------------+
|1001-01-07 00:32:20.123|
...
|1001-01-07 00:32:20.123|
+-----------------------+
```
Expected values **must be 1001-01-01 01:02:03.123** but not 1001-01-07 00:32:20.123.
Yes. After the changes:
```scala
scala> spark.read.parquet(path).show(false)
+-----------------------+
|ts |
+-----------------------+
|1001-01-01 01:02:03.123|
...
|1001-01-01 01:02:03.123|
+-----------------------+
```
Modified the test `SPARK-31159: rebasing timestamps in write` in `ParquetIOSuite` to checked reading dictionary encoded dates.
Closes #28489 from MaxGekk/fix-ts-rebase-parquet-dict-enc.
Authored-by: Max Gekk <max.gekk@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
(cherry picked from commit 5d5866b)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
HyukjinKwon
reviewed
May 11, 2020
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What changes were proposed in this pull request?
Modified the
decodeDictionaryIds()method ofVectorizedColumnReaderto handle especiallyTimestampTypewhen the passed parameterrebaseDateTimeis true. In that case, decoded milliseconds/microseconds are rebased from the hybrid calendar to Proleptic Gregorian calendar usingRebaseDateTime.rebaseJulianToGregorianMicros().Why are the changes needed?
This fixes the bug of loading timestamps before the cutover day from dictionary encoded column in parquet files. The code below forces dictionary encoding:
Load the dates back:
Expected values must be 1001-01-01 01:02:03.123 but not 1001-01-07 00:32:20.123.
Does this PR introduce any user-facing change?
Yes. After the changes:
How was this patch tested?
Modified the test
SPARK-31159: rebasing timestamps in writeinParquetIOSuiteto checked reading dictionary encoded dates.