Apache Spark - A unified analytics engine for large-scale data processing
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Herman van Hovell c604d659e1 [SPARK-23951][SQL] Use actual java class instead of string representation.
## What changes were proposed in this pull request?
This PR slightly refactors the newly added `ExprValue` API by quite a bit. The following changes are introduced:

1. `ExprValue` now uses the actual class instead of the class name as its type. This should give some more flexibility with generating code in the future.
2. Renamed `StatementValue` to `SimpleExprValue`. The statement concept is broader then an expression (untyped and it cannot be on the right hand side of an assignment), and this was not really what we were using it for. I have added a top level `JavaCode` trait that can be used in the future to reinstate (no pun intended) a statement a-like code fragment.
3. Added factory methods to the `JavaCode` companion object to make it slightly less verbose to create `JavaCode`/`ExprValue` objects. This is also what makes the diff quite large.
4. Added one more factory method to `ExprCode` to make it easier to create code-less expressions.

## How was this patch tested?
Existing tests.

Author: Herman van Hovell <hvanhovell@databricks.com>

Closes #21026 from hvanhovell/SPARK-23951.
2018-04-11 20:11:03 +08:00
.github [SPARK-18073][DOCS][WIP] Migrate wiki to spark.apache.org web site 2016-11-23 11:25:47 +00:00
assembly [SPARK-23028] Bump master branch version to 2.4.0-SNAPSHOT 2018-01-13 00:37:59 +08:00
bin [SPARK-22839][K8S] Remove the use of init-container for downloading remote dependencies 2018-03-19 11:29:56 -07:00
build [SPARK-19810][BUILD][CORE] Remove support for Scala 2.10 2017-07-13 17:06:24 +08:00
common [SPARK-23947][SQL] Add hashUTF8String convenience method to hasher classes 2018-04-09 21:07:28 -07:00
conf [SPARK-22466][SPARK SUBMIT] export SPARK_CONF_DIR while conf is default 2017-11-09 14:33:08 +09:00
core [SPARK-23816][CORE] Killed tasks should ignore FetchFailures. 2018-04-09 11:31:21 -07:00
data [SPARK-23205][ML] Update ImageSchema.readImages to correctly set alpha values for four-channel images 2018-01-25 18:15:29 -06:00
dev [SPARK-23522][PYTHON] always use sys.exit over builtin exit 2018-03-08 20:38:34 +09:00
docs [MINOR][DOCS] Fix R documentation generation instruction for roxygen2 2018-04-11 19:44:01 +08:00
examples [SPARK-22839][K8S] Remove the use of init-container for downloading remote dependencies 2018-03-19 11:29:56 -07:00
external Fix typo in Python docstring kinesis example 2018-04-09 08:04:02 -05:00
graphx [SPARK-23028] Bump master branch version to 2.4.0-SNAPSHOT 2018-01-13 00:37:59 +08:00
hadoop-cloud [SPARK-23028] Bump master branch version to 2.4.0-SNAPSHOT 2018-01-13 00:37:59 +08:00
launcher [SPARK-23834][TEST] Wait for connection before disconnect in LauncherServer test. 2018-04-02 14:35:07 -07:00
licenses [SPARK-19112][CORE] Support for ZStandard codec 2017-11-01 14:54:08 +01:00
mllib [SPARK-23944][ML] Add the set method for the two LSHModel 2018-04-10 17:26:06 -07:00
mllib-local [SPARK-23085][ML] API parity for mllib.linalg.Vectors.sparse 2018-01-19 09:28:35 -06:00
project [SPARK-14681][ML] Provide label/impurity stats for spark.ml decision tree nodes 2018-04-09 12:18:07 -07:00
python [SPARK-23847][FOLLOWUP][PYTHON][SQL] Actually test [desc|acs]_nulls_[first|last] functions in PySpark 2018-04-11 19:42:09 +08:00
R [SPARK-23770][R] Exposes repartitionByRange in SparkR 2018-03-29 19:38:28 +09:00
repl [SPARK-23538][CORE] Remove custom configuration for SSL client. 2018-03-05 15:03:27 -08:00
resource-managers [SPARK-23637][YARN] Yarn might allocate more resource if a same executor is killed multiple times. 2018-04-04 15:51:27 -07:00
sbin [SPARK-22994][K8S] Use a single image for all Spark containers. 2018-01-11 10:37:35 -08:00
sql [SPARK-23951][SQL] Use actual java class instead of string representation. 2018-04-11 20:11:03 +08:00
streaming [SPARK-23361][YARN] Allow AM to restart after initial tokens expire. 2018-03-23 13:59:21 +08:00
tools [SPARK-23028] Bump master branch version to 2.4.0-SNAPSHOT 2018-01-13 00:37:59 +08:00
.gitattributes [SPARK-3870] EOL character enforcement 2014-10-31 12:39:52 -07:00
.gitignore [SPARK-23572][DOCS] Bring "security.md" up to date. 2018-03-26 12:45:45 -07:00
.travis.yml [SPARK-18278][SCHEDULER] Spark on Kubernetes - Basic Scheduler Backend 2017-11-28 23:02:09 -08:00
appveyor.yml [SPARK-22817][R] Use fixed testthat version for SparkR tests in AppVeyor 2017-12-17 14:40:41 +09:00
CONTRIBUTING.md [SPARK-18073][DOCS][WIP] Migrate wiki to spark.apache.org web site 2016-11-23 11:25:47 +00:00
LICENSE [SPARK-19112][CORE] Support for ZStandard codec 2017-11-01 14:54:08 +01:00
NOTICE [SPARK-18278][SCHEDULER] Spark on Kubernetes - Basic Scheduler Backend 2017-11-28 23:02:09 -08:00
pom.xml [SPARK-23551][BUILD] Exclude hadoop-mapreduce-client-core dependency from orc-mapreduce 2018-03-01 17:26:39 -08:00
README.md [MINOR][DOCS] Replace non-breaking space to normal spaces that breaks rendering markdown 2017-04-03 10:09:11 +01:00
scalastyle-config.xml [SPARK-23550][CORE] Cleanup Utils. 2018-03-07 13:42:06 -08:00

Apache Spark

Spark is a fast and general cluster computing system for Big Data. 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 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. 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.)

You can build Spark using more than one thread by using the -T option with Maven, see "Parallel builds in Maven 3". 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 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" 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.

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.

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.