Apache Spark - A unified analytics engine for large-scale data processing
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Cheng Lian a9ed51178c [SPARK-5182] [SPARK-5528] [SPARK-5509] [SPARK-3575] [SQL] Parquet data source improvements
This PR adds three major improvements to Parquet data source:

1.  Partition discovery

    While reading Parquet files resides in Hive style partition directories, `ParquetRelation2` automatically discovers partitioning information and infers partition column types.

    This is also a partial work for [SPARK-5182] [1], which aims to provide first class partitioning support for the data source API.  Related code in this PR can be easily extracted to the data source API level in future versions.

1.  Schema merging

    When enabled, Parquet data source collects schema information from all Parquet part-files and tries to merge them.  Exceptions are thrown when incompatible schemas are detected.  This feature is controlled by data source option `parquet.mergeSchema`, and is enabled by default.

1.  Metastore Parquet table conversion moved to analysis phase

    This greatly simplifies the conversion logic.  `ParquetConversion` strategy can be removed once the old Parquet implementation is removed in the future.

This version of Parquet data source aims to entirely replace the old Parquet implementation.  However, the old version hasn't been removed yet.  Users can fall back to the old version by turning off SQL configuration `spark.sql.parquet.useDataSourceApi`.

Other JIRA tickets fixed as side effects in this PR:

- [SPARK-5509] [3]: `EqualTo` now uses a proper `Ordering` to compare binary types.

- [SPARK-3575] [4]: Metastore schema is now preserved and passed to `ParquetRelation2` via data source option `parquet.metastoreSchema`.

TODO:

- [ ] More test cases for partition discovery
- [x] Fix write path after data source write support (#4294) is merged

      It turned out to be non-trivial to fall back to old Parquet implementation on the write path when Parquet data source is enabled.  Since we're planning to include data source write support in 1.3.0, I simply ignored two test cases involving Parquet insertion for now.

- [ ] Fix outdated comments and documentations

PS: This PR looks big, but more than a half of the changed lines in this PR are trivial changes to test cases. To test Parquet with and without the new data source, almost all Parquet test cases are moved into wrapper driver functions. This introduces hundreds of lines of changes.

[1]: https://issues.apache.org/jira/browse/SPARK-5182
[2]: https://issues.apache.org/jira/browse/SPARK-5528
[3]: https://issues.apache.org/jira/browse/SPARK-5509
[4]: https://issues.apache.org/jira/browse/SPARK-3575

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Author: Cheng Lian <lian@databricks.com>

Closes #4308 from liancheng/parquet-partition-discovery and squashes the following commits:

b6946e6 [Cheng Lian] Fixes MiMA issues, addresses comments
8232e17 [Cheng Lian] Write support for Parquet data source
a49bd28 [Cheng Lian] Fixes spelling typo in trait name "CreateableRelationProvider"
808380f [Cheng Lian] Fixes issues introduced while rebasing
50dd8d1 [Cheng Lian] Addresses @rxin's comment, fixes UDT schema merging
adf2aae [Cheng Lian] Fixes compilation error introduced while rebasing
4e0175f [Cheng Lian] Fixes Python Parquet API, we need Py4J array to call varargs method
0d8ec1d [Cheng Lian] Adds more test cases
b35c8c6 [Cheng Lian] Fixes some typos and outdated comments
dd704fd [Cheng Lian] Fixes Python Parquet API
596c312 [Cheng Lian] Uses switch to control whether use Parquet data source or not
7d0f7a2 [Cheng Lian] Fixes Metastore Parquet table conversion
a1896c7 [Cheng Lian] Fixes all existing Parquet test suites except for ParquetMetastoreSuite
5654c9d [Cheng Lian] Draft version of Parquet partition discovery and schema merging
2015-02-05 15:29:56 -08:00
assembly [SPARK-4809] Rework Guava library shading. 2015-01-28 00:29:29 -08:00
bagel [SPARK-4048] Enhance and extend hadoop-provided profile. 2015-01-08 17:15:13 -08:00
bin [SPARK-5341] Use maven coordinates as dependencies in spark-shell and spark-submit 2015-02-03 22:39:17 -08:00
build [SPARK-5474][Build]curl should support URL redirection in build/mvn 2015-02-05 12:03:13 -08:00
conf [SPARK-5422] Add support for sending Graphite metrics via UDP 2015-01-31 23:41:05 -08:00
core [SPARK-5182] [SPARK-5528] [SPARK-5509] [SPARK-3575] [SQL] Parquet data source improvements 2015-02-05 15:29:56 -08:00
data/mllib SPARK-2363. Clean MLlib's sample data files 2014-07-13 19:27:43 -07:00
dev [SPARK-5474][Build]curl should support URL redirection in build/mvn 2015-02-05 12:03:13 -08:00
docker [SPARK-1342] Scala 2.10.4 2014-04-01 18:35:50 -07:00
docs [Branch-1.3] [DOC] doc fix for date 2015-02-05 12:42:27 -08:00
ec2 [SPARK-5434] [EC2] Preserve spaces in EC2 path 2015-01-28 12:56:03 -08:00
examples [SPARK-5604[MLLIB] remove checkpointDir from LDA 2015-02-05 15:07:33 -08:00
external [SPARK-4707][STREAMING] Reliable Kafka Receiver can lose data if the blo... 2015-02-04 14:20:44 -08:00
extras [SPARK-5155] Build fails with spark-ganglia-lgpl profile 2015-02-01 17:53:56 -08:00
graphx [SPARK-4795][Core] Redesign the "primitive type => Writable" implicit APIs to make them be activated automatically 2015-02-03 20:17:12 -08:00
mllib [SPARK-5604[MLLIB] remove checkpointDir from LDA 2015-02-05 15:07:33 -08:00
network [SPARK-3996]: Shade Jetty in Spark deliverables 2015-02-01 21:13:57 -08:00
project [SQL][Hiveconsole] Bring hive console code up to date and update README.md 2015-02-04 15:13:54 -08:00
python [SPARK-5182] [SPARK-5528] [SPARK-5509] [SPARK-3575] [SQL] Parquet data source improvements 2015-02-05 15:29:56 -08:00
repl [SPARK-5612][SQL] Move DataFrame implicit functions into SQLContext.implicits. 2015-02-04 23:44:34 -08:00
sbin [SPARK-5176] The thrift server does not support cluster mode 2015-02-01 17:57:31 -08:00
sbt Adde LICENSE Header to build/mvn, build/sbt and sbt/sbt 2014-12-29 10:48:53 -08:00
sql [SPARK-5182] [SPARK-5528] [SPARK-5509] [SPARK-3575] [SQL] Parquet data source improvements 2015-02-05 15:29:56 -08:00
streaming [Minor] Fix incorrect warning log 2015-02-04 00:52:41 -08:00
tools SPARK-4159 [CORE] Maven build doesn't run JUnit test suites 2015-01-06 12:02:08 -08:00
yarn SPARK-3996: Add jetty servlet and continuations. 2015-02-02 21:01:36 -08:00
.gitattributes [SPARK-3870] EOL character enforcement 2014-10-31 12:39:52 -07:00
.gitignore [SPARK-4501][Core] - Create build/mvn to automatically download maven/zinc/scalac 2014-12-27 13:26:38 -08:00
.rat-excludes [HOTFIX] Fix RAT exclusion for known_translations file 2014-12-16 23:00:25 -08:00
CONTRIBUTING.md [Docs] minor grammar fix 2014-09-17 12:33:09 -07:00
LICENSE SPARK-3926 [CORE] Reopened: result of JavaRDD collectAsMap() is not serializable 2014-12-08 16:13:03 -08:00
make-distribution.sh [SPARK-5188][BUILD] make-distribution.sh should support curl, not only wget to get Tachyon 2015-01-28 12:43:22 -08:00
NOTICE SPARK-1827. LICENSE and NOTICE files need a refresh to contain transitive dependency info 2014-05-14 09:38:33 -07:00
pom.xml SPARK-5607: Update to Kryo 2.24.0 to avoid including objenesis 1.2. 2015-02-04 22:39:44 -08:00
README.md [Docs] Fix Building Spark link text 2015-02-02 12:33:49 -08:00
scalastyle-config.xml [Core] Upgrading ScalaStyle version to 0.5 and removing SparkSpaceAfterCommentStartChecker. 2014-10-16 02:05:44 -04:00
tox.ini [SPARK-3073] [PySpark] use external sort in sortBy() and sortByKey() 2014-08-26 16:57:40 -07:00

Apache Spark

Spark is a fast and general cluster computing system for Big Data. It provides high-level APIs in Scala, Java, and Python, 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 structured data processing, MLlib for machine learning, GraphX for graph processing, and Spark Streaming for stream processing.

http://spark.apache.org/

Online Documentation

You can find the latest Spark documentation, including a programming guide, on the project web page and project wiki. This README file only contains basic setup instructions.

Building Spark

Spark is built using Apache Maven. To build Spark and its example programs, run:

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".

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 1000:

scala> sc.parallelize(1 to 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 1000:

>>> sc.parallelize(range(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-cluster" or "yarn-client" 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 all automated tests.

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" for detailed guidance on building for a particular distribution of Hadoop, including building for particular Hive and Hive Thriftserver distributions. See also "Third Party Hadoop Distributions" for guidance on building a Spark application that works with a particular distribution.

Configuration

Please refer to the Configuration guide in the online documentation for an overview on how to configure Spark.