Apache Spark - A unified analytics engine for large-scale data processing
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Wenchen Fan 4b015e8d7d [SPARK-36535][SQL] Refine the sql reference doc
### What changes were proposed in this pull request?

Refine the SQL reference doc:
- remove useless subitems in the sidebar
- remove useless sub-menu-pages (e.g. `sql-ref-syntax-aux.md`)
- avoid using `#####` in `sql-ref-literals.md`

### Why are the changes needed?

The subitems in the sidebar are quite useless, as the menu page serves the same functionalities:
<img width="1040" alt="WX20210817-2358402x" src="https://user-images.githubusercontent.com/3182036/129765924-d7e69bc1-e351-4581-a6de-f2468022f372.png">
It's also extra work to keep the manu page and sidebar subitems in sync (The ANSI compliance page is already out of sync).

The sub-menu-pages are only referenced by the sidebar, and duplicates the content of the menu page. As a result, the `sql-ref-syntax-aux.md` is already outdated compared to the menu page. It's easier to just look at the menu page.

The `#####` is not rendered properly:
<img width="776" alt="WX20210818-0001192x" src="https://user-images.githubusercontent.com/3182036/129766760-6f385443-e597-44aa-888d-14d128d45f84.png">
It's better to avoid using it.

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

N/A

Closes #33767 from cloud-fan/doc.

Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
2021-08-17 12:46:38 -07:00
.github [SPARK-36441][INFRA] Fix GA failure related to downloading lintr dependencies 2021-08-06 10:49:27 +09:00
.idea [SPARK-35223] Add IssueNavigationLink 2021-04-26 21:51:21 +08:00
assembly [SPARK-35996][BUILD] Setting version to 3.3.0-SNAPSHOT 2021-07-02 13:47:36 -07:00
bin [SPARK-34688][PYTHON] Upgrade to Py4J 0.10.9.2 2021-03-11 09:51:41 -06:00
binder [SPARK-35588][PYTHON][DOCS] Merge Binder integration and quickstart notebook for pandas API on Spark 2021-06-24 10:17:22 +09:00
build [SPARK-36393][BUILD] Try to raise memory for GHA 2021-08-05 01:31:35 -07:00
common [SPARK-35548][CORE][SHUFFLE] Handling new attempt has started error message in BlockPushErrorHandler in client 2021-08-16 13:58:48 -05:00
conf [SPARK-36377][DOCS] Re-document "Options read in YARN client/cluster mode" section in spark-env.sh.template 2021-08-10 11:05:39 +09:00
core [SPARK-35548][CORE][SHUFFLE] Handling new attempt has started error message in BlockPushErrorHandler in client 2021-08-16 13:58:48 -05:00
data [SPARK-22666][ML][SQL] Spark datasource for image format 2018-09-05 11:59:00 -07:00
dev Update Spark key negotiation protocol 2021-08-11 18:04:55 -05:00
docs [SPARK-36535][SQL] Refine the sql reference doc 2021-08-17 12:46:38 -07:00
examples [SPARK-36455][SS] Provide an example of complex session window via flatMapGroupsWithState 2021-08-09 19:39:49 +09:00
external [SPARK-36524][SQL] Common class for ANSI interval types 2021-08-17 12:27:56 +03:00
graphx [SPARK-36420][GRAPHX] Use isEmpty to improve performance in Pregel‘s superstep 2021-08-06 12:20:47 +09:00
hadoop-cloud [SPARK-36068][BUILD][TEST] No tests in hadoop-cloud run unless hadoop-3.2 profile is activated explicitly 2021-08-05 09:39:28 +09:00
launcher [SPARK-36362][CORE][SQL][TESTS] Omnibus Java code static analyzer warning fixes 2021-07-31 22:35:57 -07:00
licenses [SPARK-32435][PYTHON] Remove heapq3 port from Python 3 2020-07-27 20:10:13 +09:00
licenses-binary [SPARK-35150][ML] Accelerate fallback BLAS with dev.ludovic.netlib 2021-04-27 14:00:59 -05:00
mllib [SPARK-36418][SQL] Use CAST in parsing of dates/timestamps with default pattern 2021-08-16 23:29:33 +08:00
mllib-local [SPARK-35996][BUILD] Setting version to 3.3.0-SNAPSHOT 2021-07-02 13:47:36 -07:00
project [SPARK-36393][BUILD][FOLLOW-UP] Try to raise memory for GHA 2021-08-05 20:09:30 -07:00
python [SPARK-36370][PYTHON] _builtin_table directly imported from pandas instead of being redefined 2021-08-17 10:46:49 -07:00
R [SPARK-36154][DOCS] Documenting week and quarter as valid formats in pyspark sql/functions trunc 2021-07-15 16:51:11 +03:00
repl [SPARK-35996][BUILD] Setting version to 3.3.0-SNAPSHOT 2021-07-02 13:47:36 -07:00
resource-managers [SPARK-36052][K8S][FOLLOWUP] Update config version to 3.2.0 2021-08-17 10:28:02 +09:00
sbin [SPARK-34688][PYTHON] Upgrade to Py4J 0.10.9.2 2021-03-11 09:51:41 -06:00
sql Revert "[SPARK-35028][SQL] ANSI mode: disallow group by aliases" 2021-08-17 20:23:49 +08:00
streaming [SPARK-36362][CORE][SQL][TESTS] Omnibus Java code static analyzer warning fixes 2021-07-31 22:35:57 -07:00
tools [SPARK-35996][BUILD] Setting version to 3.3.0-SNAPSHOT 2021-07-02 13:47:36 -07:00
.asf.yaml [MINOR][INFRA] Add enabled_merge_buttons to .asf.yaml explicitly 2021-07-23 15:29:44 -07:00
.gitattributes [SPARK-30653][INFRA][SQL] EOL character enforcement for java/scala/xml/py/R files 2020-01-27 10:20:51 -08:00
.gitignore [SPARK-36092][INFRA][BUILD][PYTHON] Migrate to GitHub Actions with Codecov from Jenkins 2021-08-01 21:37:19 +09:00
appveyor.yml [SPARK-33757][INFRA][R][FOLLOWUP] Provide more simple solution 2020-12-13 17:27:39 -08:00
CONTRIBUTING.md [MINOR][DOCS] Tighten up some key links to the project and download pages to use HTTPS 2019-05-21 10:56:42 -07:00
LICENSE [SPARK-32435][PYTHON] Remove heapq3 port from Python 3 2020-07-27 20:10:13 +09:00
LICENSE-binary [SPARK-35295][ML] Replace fully com.github.fommil.netlib by dev.ludovic.netlib:2.0 2021-05-12 08:59:36 -05:00
NOTICE [SPARK-29674][CORE] Update dropwizard metrics to 4.1.x for JDK 9+ 2019-11-03 15:13:06 -08:00
NOTICE-binary [SPARK-29674][CORE] Update dropwizard metrics to 4.1.x for JDK 9+ 2019-11-03 15:13:06 -08:00
pom.xml [SPARK-36502][SQL] Remove jaxb-api from sql/catalyst module 2021-08-13 12:31:09 +09:00
README.md [MINOR][DOCS] More correct results for GitHub Actions build link at README.md 2021-08-14 22:05:16 -07:00
scalastyle-config.xml [SPARK-35894][BUILD] Introduce new style enforce to not import scala.collection.Seq/IndexedSeq 2021-06-26 09:41:16 +09:00

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, pandas API on Spark for pandas workloads, MLlib for machine learning, GraphX for graph processing, and Structured Streaming for stream processing.

https://spark.apache.org/

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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.