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### What changes were proposed in this pull request? In the PR, I propose new options for the Parquet datasource: 1. `datetimeRebaseMode` 2. `int96RebaseMode` Both options influence on loading ancient dates and timestamps column values from parquet files. The `datetimeRebaseMode` option impacts on loading values of the `DATE`, `TIMESTAMP_MICROS` and `TIMESTAMP_MILLIS` types, `int96RebaseMode` impacts on loading of `INT96` timestamps. The options support the same values as the SQL configs `spark.sql.legacy.parquet.datetimeRebaseModeInRead` and `spark.sql.legacy.parquet.int96RebaseModeInRead` namely; - `"LEGACY"`, when an option is set to this value, Spark rebases dates/timestamps from the legacy hybrid calendar (Julian + Gregorian) to the Proleptic Gregorian calendar. - `"CORRECTED"`, dates/timestamps are read AS IS from parquet files. - `"EXCEPTION"`, when it is set as an option value, Spark will fail the reading if it sees ancient dates/timestamps that are ambiguous between the two calendars. ### Why are the changes needed? 1. New options will allow to load parquet files from at least two sources in different rebasing modes in the same query. For instance: ```scala val df1 = spark.read.option("datetimeRebaseMode", "legacy").parquet(folder1) val df2 = spark.read.option("datetimeRebaseMode", "corrected").parquet(folder2) df1.join(df2, ...) ``` Before the changes, it is impossible because the SQL config `spark.sql.legacy.parquet.datetimeRebaseModeInRead` influences on both reads. 2. Mixing of Dataset/DataFrame and RDD APIs should become possible. Since SQL configs are not propagated through RDDs, the following code fails on ancient timestamps: ```scala spark.conf.set("spark.sql.legacy.parquet.datetimeRebaseModeInRead", "legacy") spark.read.parquet(folder).distinct.rdd.collect() ``` ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? By running the modified test suites: ``` $ build/sbt "sql/test:testOnly *ParquetRebaseDatetimeV1Suite" $ build/sbt "sql/test:testOnly *ParquetRebaseDatetimeV2Suite" ``` Closes #31489 from MaxGekk/parquet-rebase-options. Authored-by: Max Gekk <max.gekk@gmail.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com> |
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Apache Spark
Spark is a unified analytics engine for large-scale data processing. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Structured Streaming for stream processing.
Online Documentation
You can find the latest Spark documentation, including a programming guide, on the project web page. This README file only contains basic setup instructions.
Building Spark
Spark is built using Apache Maven. To build Spark and its example programs, run:
./build/mvn -DskipTests clean package
(You do not need to do this if you downloaded a pre-built package.)
More detailed documentation is available from the project site, at "Building Spark".
For general development tips, including info on developing Spark using an IDE, see "Useful Developer Tools".
Interactive Scala Shell
The easiest way to start using Spark is through the Scala shell:
./bin/spark-shell
Try the following command, which should return 1,000,000,000:
scala> spark.range(1000 * 1000 * 1000).count()
Interactive Python Shell
Alternatively, if you prefer Python, you can use the Python shell:
./bin/pyspark
And run the following command, which should also return 1,000,000,000:
>>> spark.range(1000 * 1000 * 1000).count()
Example Programs
Spark also comes with several sample programs in the examples
directory.
To run one of them, use ./bin/run-example <class> [params]
. For example:
./bin/run-example SparkPi
will run the Pi example locally.
You can set the MASTER environment variable when running examples to submit
examples to a cluster. This can be a mesos:// or spark:// URL,
"yarn" to run on YARN, and "local" to run
locally with one thread, or "local[N]" to run locally with N threads. You
can also use an abbreviated class name if the class is in the examples
package. For instance:
MASTER=spark://host:7077 ./bin/run-example SparkPi
Many of the example programs print usage help if no params are given.
Running Tests
Testing first requires building Spark. Once Spark is built, tests can be run using:
./dev/run-tests
Please see the guidance on how to run tests for a module, or individual tests.
There is also a Kubernetes integration test, see resource-managers/kubernetes/integration-tests/README.md
A Note About Hadoop Versions
Spark uses the Hadoop core library to talk to HDFS and other Hadoop-supported storage systems. Because the protocols have changed in different versions of Hadoop, you must build Spark against the same version that your cluster runs.
Please refer to the build documentation at "Specifying the Hadoop Version and Enabling YARN" for detailed guidance on building for a particular distribution of Hadoop, including building for particular Hive and Hive Thriftserver distributions.
Configuration
Please refer to the Configuration Guide in the online documentation for an overview on how to configure Spark.
Contributing
Please review the Contribution to Spark guide for information on how to get started contributing to the project.