Apache Spark - A unified analytics engine for large-scale data processing
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Cheng Lian 11caf1ce29 [SPARK-4176] [SQL] [MINOR] Should use unscaled Long to write decimals for precision <= 18 rather than 8
This PR fixes a minor bug introduced in #7455: when writing decimals, we should use the unscaled Long for better performance when the precision <= 18 rather than 8 (should be a typo). This bug doesn't affect correctness, but hurts Parquet decimal writing performance.

This PR also replaced similar magic numbers with newly defined constants.

Author: Cheng Lian <lian@databricks.com>

Closes #8031 from liancheng/spark-4176/minor-fix-for-writing-decimals and squashes the following commits:

10d4ea3 [Cheng Lian] Should use unscaled Long to write decimals for precision <= 18 rather than 8
2015-08-08 18:09:48 +08:00
assembly [SPARK-7801] [BUILD] Updating versions to SPARK 1.5.0 2015-06-03 10:11:27 -07:00
bagel [SPARK-7801] [BUILD] Updating versions to SPARK 1.5.0 2015-06-03 10:11:27 -07:00
bin [SPARK-9270] [PYSPARK] allow --name option in pyspark 2015-07-24 11:56:55 -07:00
build [SPARK-9633] [BUILD] SBT download locations outdated; need an update 2015-08-06 23:43:52 +01:00
conf [SPARK-9558][DOCS]Update docs to follow the increase of memory defaults. 2015-08-03 12:53:44 -07:00
core [SPARK-9731] Standalone scheduling incorrect cores if spark.executor.cores is not set 2015-08-07 23:36:26 -07:00
data/mllib [MLLIB] [DOC] Seed fix in mllib naive bayes example 2015-07-18 10:12:48 -07:00
dev [SPARK-6485] [MLLIB] [PYTHON] Add CoordinateMatrix/RowMatrix/IndexedRowMatrix to PySpark. 2015-08-04 16:30:03 -07:00
docker [SPARK-8954] [BUILD] Remove unneeded deb repository from Dockerfile to fix build error in docker. 2015-07-13 12:01:23 -07:00
docs Fix doc typo 2015-08-06 21:03:47 -07:00
ec2 [SPARK-9562] Change reference to amplab/spark-ec2 from mesos/ 2015-08-04 09:40:07 -07:00
examples [SPARK-8069] [ML] Add multiclass thresholds for ProbabilisticClassifier 2015-08-04 10:12:22 -07:00
external [DOCS] [STREAMING] make the existing parameter docs for OffsetRange ac… 2015-08-06 14:37:25 -07:00
extras [SPARK-9556] [SPARK-9619] [SPARK-9624] [STREAMING] Make BlockGenerator more robust and make all BlockGenerators subscribe to rate limit updates 2015-08-06 14:35:30 -07:00
graphx [SPARK-3190] [GRAPHX] Fix VertexRDD.count() overflow regression 2015-08-03 23:07:32 -07:00
launcher [SPARK-9263] Added flags to exclude dependencies when using --packages 2015-08-03 17:42:03 -07:00
mllib [SPARK-9719] [ML] Clean up Naive Bayes doc 2015-08-07 17:21:12 -07:00
network [SPARK-9534] [BUILD] Enable javac lint for scalac parity; fix a lot of build warnings, 1.5.0 edition 2015-08-04 12:02:26 +01:00
project [SPARK-9602] remove "Akka/Actor" words from comments 2015-08-04 14:54:11 -07:00
python [SPARK-9733][SQL] Improve physical plan explain for data sources 2015-08-07 13:41:45 -07:00
R [SPARK-9700] Pick default page size more intelligently. 2015-08-06 23:18:29 -07:00
repl [SPARK-9602] remove "Akka/Actor" words from comments 2015-08-04 14:54:11 -07:00
sbin [SPARK-8064] [SQL] Build against Hive 1.2.1 2015-08-03 15:24:42 -07:00
sbt Adde LICENSE Header to build/mvn, build/sbt and sbt/sbt 2014-12-29 10:48:53 -08:00
sql [SPARK-4176] [SQL] [MINOR] Should use unscaled Long to write decimals for precision <= 18 rather than 8 2015-08-08 18:09:48 +08:00
streaming [SPARK-9639] [STREAMING] Fix a potential NPE in Streaming JobScheduler 2015-08-06 14:39:36 -07:00
tools [SPARK-9015] [BUILD] Clean project import in scala ide 2015-07-16 18:42:41 +01:00
unsafe [SPARK-9700] Pick default page size more intelligently. 2015-08-06 23:18:29 -07:00
yarn [SPARK-9519] [YARN] Confirm stop sc successfully when application was killed 2015-08-05 10:16:12 -07:00
.gitattributes [SPARK-3870] EOL character enforcement 2014-10-31 12:39:52 -07:00
.gitignore [SPARK-8495] [SPARKR] Add a .lintr file to validate the SparkR files and the lint-r script 2015-06-20 16:10:14 -07:00
.rat-excludes [SPARK-6123] [SPARK-6775] [SPARK-6776] [SQL] Refactors Parquet read path for interoperability and backwards-compatibility 2015-07-08 15:51:01 -07:00
CONTRIBUTING.md [SPARK-6889] [DOCS] CONTRIBUTING.md updates to accompany contribution doc updates 2015-04-21 22:34:31 -07:00
LICENSE [SPARK-8709] Exclude hadoop-client's mockito-all dependency 2015-06-29 14:07:55 -07:00
make-distribution.sh [SPARK-9199] [CORE] Update Tachyon dependency from 0.6.4 -> 0.7.0 2015-07-30 16:32:40 -07:00
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-8064] [BUILD] Follow-up. Undo change from SPARK-9507 that was accidentally reverted 2015-08-04 12:23:04 +01:00
pylintrc [SPARK-9116] [SQL] [PYSPARK] support Python only UDT in __main__ 2015-07-29 22:30:49 -07:00
README.md Update README to include DataFrames and zinc. 2015-05-31 23:55:45 -07:00
scalastyle-config.xml [SPARK-8962] Add Scalastyle rule to ban direct use of Class.forName; fix existing uses 2015-07-14 16:08:17 -07:00
tox.ini [SPARK-7427] [PYSPARK] Make sharedParams match in Scala, Python 2015-05-10 19:18:32 -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 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 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:

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".

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 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. 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.