## What changes were proposed in this pull request?

Auto generated Oracle schema some times not we expect:

- `number(1)` auto mapped to BooleanType, some times it's not we expect, per [SPARK-20921](https://issues.apache.org/jira/browse/SPARK-20921).
-  `number` auto mapped to Decimal(38,10), It can't read big data, per [SPARK-20427](https://issues.apache.org/jira/browse/SPARK-20427).

This PR fix this issue by custom schema as follows:
```scala
val props = new Properties()
props.put("customSchema", "ID decimal(38, 0), N1 int, N2 boolean")
val dfRead = spark.read.schema(schema).jdbc(jdbcUrl, "tableWithCustomSchema", props)
dfRead.show()
```
or
```sql
CREATE TEMPORARY VIEW tableWithCustomSchema
USING org.apache.spark.sql.jdbc
OPTIONS (url '$jdbcUrl', dbTable 'tableWithCustomSchema', customSchema'ID decimal(38, 0), N1 int, N2 boolean')
```

## How was this patch tested?

unit tests

Author: Yuming Wang <wgyumg@gmail.com>

Closes #18266 from wangyum/SPARK-20427.

## What changes were proposed in this pull request?

1. Removing all redundant throws declarations from Java codebase.
2. Removing dead code made visible by this from `ShuffleExternalSorter#closeAndGetSpills`

## How was this patch tested?

Build still passes.

Author: Armin <me@obrown.io>

Closes #19182 from original-brownbear/SPARK-21970.

## What changes were proposed in this pull request?

Put Kafka 0.8 support behind a kafka-0-8 profile.

## How was this patch tested?

Existing tests, but, until PR builder and Jenkins configs are updated the effect here is to not build or test Kafka 0.8 support at all.

Author: Sean Owen <sowen@cloudera.com>

Closes #19134 from srowen/SPARK-21893.

## What changes were proposed in this pull request?
Modified `CrossValidator` and `TrainValidationSplit` to be able to evaluate models in parallel for a given parameter grid.  The level of parallelism is controlled by a parameter `numParallelEval` used to schedule a number of models to be trained/evaluated so that the jobs can be run concurrently.  This is a naive approach that does not check the cluster for needed resources, so care must be taken by the user to tune the parameter appropriately.  The default value is `1` which will train/evaluate in serial.

## How was this patch tested?
Added unit tests for CrossValidator and TrainValidationSplit to verify that model selection is the same when run in serial vs parallel.  Manual testing to verify tasks run in parallel when param is > 1. Added parameter usage to relevant examples.

Author: Bryan Cutler <cutlerb@gmail.com>

Closes #16774 from BryanCutler/parallel-model-eval-SPARK-19357.

## What changes were proposed in this pull request?

This PR adds ML examples for the FeatureHasher transform in Scala, Java, Python.

## How was this patch tested?

Manually ran examples and verified that output is consistent for different APIs

Author: Bryan Cutler <cutlerb@gmail.com>

Closes #19024 from BryanCutler/ml-examples-FeatureHasher-SPARK-21810.

This version fixes a few issues in the import order checker; it provides
better error messages, and detects more improper ordering (thus the need
to change a lot of files in this patch). The main fix is that it correctly
complains about the order of packages vs. classes.

As part of the above, I moved some "SparkSession" import in ML examples
inside the "$example on$" blocks; that didn't seem consistent across
different source files to start with, and avoids having to add more on/off blocks
around specific imports.

The new scalastyle also seems to have a better header detector, so a few
license headers had to be updated to match the expected indentation.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #18943 from vanzin/SPARK-21731.

## What changes were proposed in this pull request?

Address scapegoat warnings for:
- BigDecimal double constructor
- Catching NPE
- Finalizer without super
- List.size is O(n)
- Prefer Seq.empty
- Prefer Set.empty
- reverse.map instead of reverseMap
- Type shadowing
- Unnecessary if condition.
- Use .log1p
- Var could be val

In some instances like Seq.empty, I avoided making the change even where valid in test code to keep the scope of the change smaller. Those issues are concerned with performance and it won't matter for tests.

## How was this patch tested?

Existing tests

Author: Sean Owen <sowen@cloudera.com>

Closes #18635 from srowen/Scapegoat1.

## What changes were proposed in this pull request?

- Remove Scala 2.10 build profiles and support
- Replace some 2.10 support in scripts with commented placeholders for 2.12 later
- Remove deprecated API calls from 2.10 support
- Remove usages of deprecated context bounds where possible
- Remove Scala 2.10 workarounds like ScalaReflectionLock
- Other minor Scala warning fixes

## How was this patch tested?

Existing tests

Author: Sean Owen <sowen@cloudera.com>

Closes #17150 from srowen/SPARK-19810.

## What changes were proposed in this pull request?

This PR cleans up a few Java linter errors for Apache Spark 2.2 release.

## How was this patch tested?

```bash
$ dev/lint-java
Using `mvn` from path: /usr/local/bin/mvn
Checkstyle checks passed.
```

We can check the result at Travis CI, [here](https://travis-ci.org/dongjoon-hyun/spark/builds/244297894).

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #18345 from dongjoon-hyun/fix_lint_java_2.

the original code cant visit the last element of the"parts" array.
so the v[v.length–1] always equals 0

## What changes were proposed in this pull request?
change the recycle range from (1 to parts.length-1) to (1 to parts.length)

## How was this patch tested?

debug it in eclipse (´〜｀*) zzz.

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: junzhi lu <452756565@qq.com>

Closes #18237 from masterwugui/patch-1.

## What changes were proposed in this pull request?

- Add Scala, Python and Java examples for `partitionBy`, `sortBy` and `bucketBy`.
- Add _Bucketing, Sorting and Partitioning_ section to SQL Programming Guide
- Remove bucketing from Unsupported Hive Functionalities.

## How was this patch tested?

Manual tests, docs build.

Author: zero323 <zero323@users.noreply.github.com>

Closes #17938 from zero323/DOCS-BUCKETING-AND-PARTITIONING.

## What changes were proposed in this pull request?
1, add an example for sparkr `decisionTree`
2, document it in user guide

## How was this patch tested?
local submit

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #18067 from zhengruifeng/dt_example.

## What changes were proposed in this pull request?

Add Structured Streaming Kafka Source to the `examples` project so that people can run `bin/run-example StructuredKafkaWordCount ...`.

## How was this patch tested?

manually tested it.

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #18101 from zsxwing/add-missing-example-dep.

## What changes were proposed in this pull request?

The license is not at the top in some files. and it will be best if we update these places of the ASF header to be consistent with other files.

## How was this patch tested?

manual tests

Author: zuotingbing <zuo.tingbing9@zte.com.cn>

Closes #18012 from zuotingbing/spark-license.

## What changes were proposed in this pull request?
Add docs and examples for ```ml.stat.Correlation``` and ```ml.stat.ChiSquareTest```.

## How was this patch tested?
Generate docs and run examples manually, successfully.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #17994 from yanboliang/spark-20505.

Update ALS examples illustrating use of "recommendForAllX" methods.

## How was this patch tested?
Built and ran examples locally

Author: Nick Pentreath <nickp@za.ibm.com>

Closes #17950 from MLnick/SPARK-20553-update-als-examples.

## What changes were proposed in this pull request?

Remove uses of scala.language.reflectiveCalls that are either unnecessary or probably resulting in more complex code. This turned out to be less significant than I thought, but, still worth a touch-up.

## How was this patch tested?

Existing tests.

Author: Sean Owen <sowen@cloudera.com>

Closes #17949 from srowen/SPARK-20554.

## What changes were proposed in this pull request?

Any Dataset/DataFrame batch query with the operation `withWatermark` does not execute because the batch planner does not have any rule to explicitly handle the EventTimeWatermark logical plan.
The right solution is to simply remove the plan node, as the watermark should not affect any batch query in any way.

Changes:
- In this PR, we add a new rule `EliminateEventTimeWatermark` to check if we need to ignore the event time watermark. We will ignore watermark in any batch query.

Depends upon:
- [SPARK-20672](https://issues.apache.org/jira/browse/SPARK-20672). We can not add this rule into analyzer directly, because streaming query will be copied to `triggerLogicalPlan ` in every trigger, and the rule will be applied to `triggerLogicalPlan` mistakenly.

Others:
- A typo fix in example.

## How was this patch tested?

add new unit test.

Author: uncleGen <hustyugm@gmail.com>

Closes #17896 from uncleGen/SPARK-20373.

[SPARK-20015][SPARKR][SS][DOC][EXAMPLE] Document R Structured Streaming (experimental) in R vignettes and R & SS programming guide, R example

## What changes were proposed in this pull request?

Add
- R vignettes
- R programming guide
- SS programming guide
- R example

Also disable spark.als in vignettes for now since it's failing (SPARK-20402)

## How was this patch tested?

manually

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17814 from felixcheung/rdocss.

## What changes were proposed in this pull request?

Fix build warnings primarily related to Breeze 0.13 operator changes, Java style problems

## How was this patch tested?

Existing tests

Author: Sean Owen <sowen@cloudera.com>

Closes #17803 from srowen/SPARK-20523.

Add PCA and SVD to PySpark's wrappers for `RowMatrix` and `IndexedRowMatrix` (SVD only).

Based on #7963, updated.

## How was this patch tested?

New doc tests and unit tests. Ran all examples locally.

Author: MechCoder <manojkumarsivaraj334@gmail.com>
Author: Nick Pentreath <nickp@za.ibm.com>

Closes #17621 from MLnick/SPARK-6227-pyspark-svd-pca.

## What changes were proposed in this pull request?

Add a new section for fpm
Add Example for FPGrowth in scala and Java

updated: Rewrite transform to be more compact.

## How was this patch tested?

local doc generation.

Author: Yuhao Yang <yuhao.yang@intel.com>

Closes #17130 from hhbyyh/fpmdoc.

This patch bumps the master branch version to `2.3.0-SNAPSHOT`.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #17753 from JoshRosen/SPARK-20453.

## What changes were proposed in this pull request?

Document  fpGrowth in:

- vignettes
- programming guide
- code example

## How was this patch tested?

Manual tests.

Author: zero323 <zero323@users.noreply.github.com>

Closes #17557 from zero323/SPARK-20208.

## What changes were proposed in this pull request?

Extra accessors in java bean class causes incorrect encoder generation, which corrupted the state when using timeouts.

## How was this patch tested?
manually ran the example

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #17676 from tdas/SPARK-20377.

## What changes were proposed in this pull request?

This PR proposes corrections related to JSON APIs as below:

- Rendering links in Python documentation
- Replacing `RDD` to `Dataset` in programing guide
- Adding missing description about JSON Lines consistently in `DataFrameReader.json` in Python API
- De-duplicating little bit of `DataFrameReader.json` in Scala/Java API

## How was this patch tested?

Manually build the documentation via `jekyll build`. Corresponding snapstops will be left on the codes.

Note that currently there are Javadoc8 breaks in several places. These are proposed to be handled in https://github.com/apache/spark/pull/17477. So, this PR does not fix those.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17602 from HyukjinKwon/minor-json-documentation.

[SPARK-20156][CORE][SQL][STREAMING][MLLIB] Java String toLowerCase "Turkish locale bug" causes Spark problems

## What changes were proposed in this pull request?

Add Locale.ROOT to internal calls to String `toLowerCase`, `toUpperCase`, to avoid inadvertent locale-sensitive variation in behavior (aka the "Turkish locale problem").

The change looks large but it is just adding `Locale.ROOT` (the locale with no country or language specified) to every call to these methods.

## How was this patch tested?

Existing tests.

Author: Sean Owen <sowen@cloudera.com>

Closes #17527 from srowen/SPARK-20156.

## What changes were proposed in this pull request?

Came across the term "slice" when running some spark scala code. Consequently, a Google search indicated that "slices" and "partitions" refer to the same things; indeed see:

- [This issue](https://issues.apache.org/jira/browse/SPARK-1701)
- [This pull request](https://github.com/apache/spark/pull/2305)
- [This StackOverflow answer](http://stackoverflow.com/questions/23436640/what-is-the-difference-between-an-rdd-partition-and-a-slice) and [this one](http://stackoverflow.com/questions/24269495/what-are-the-differences-between-slices-and-partitions-of-rdds)

Thus this pull request fixes the occurrence of slice I came accross. Nonetheless, [it would appear](https://github.com/apache/spark/search?utf8=%E2%9C%93&q=slice&type=) there are still many references to "slice/slices" - thus I thought I'd raise this Pull Request to address the issue (sorry if this is the wrong place, I'm not too familar with raising apache issues).

## How was this patch tested?

(Not tested locally - only a minor exception message change.)

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: asmith26 <asmith26@users.noreply.github.com>

Closes #17565 from asmith26/master.

[SPARK-20258][DOC][SPARKR] Fix SparkR logistic regression example in programming guide (did not converge)

## What changes were proposed in this pull request?

SparkR logistic regression example did not converge in programming guide (for IRWLS). All estimates are essentially zero:

```
training2 <- read.df("data/mllib/sample_binary_classification_data.txt", source = "libsvm")
df_list2 <- randomSplit(training2, c(7,3), 2)
binomialDF <- df_list2[[1]]
binomialTestDF <- df_list2[[2]]
binomialGLM <- spark.glm(binomialDF, label ~ features, family = "binomial")

17/04/07 11:42:03 WARN WeightedLeastSquares: Cholesky solver failed due to singular covariance matrix. Retrying with Quasi-Newton solver.

> summary(binomialGLM)

Coefficients:
                 Estimate
(Intercept)    9.0255e+00
features_0     0.0000e+00
features_1     0.0000e+00
features_2     0.0000e+00
features_3     0.0000e+00
features_4     0.0000e+00
features_5     0.0000e+00
features_6     0.0000e+00
features_7     0.0000e+00
```

Author: actuaryzhang <actuaryzhang10@gmail.com>

Closes #17571 from actuaryzhang/programGuide2.

## What changes were proposed in this pull request?
Add Tweedie example for SparkR in programming guide.
The doc was already updated in #17103.

Author: actuaryzhang <actuaryzhang10@gmail.com>

Closes #17553 from actuaryzhang/programGuide.

## What changes were proposed in this pull request?

Fix typo in hive examples from "DaraFrames" to "DataFrames"

## How was this patch tested?

N/A

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: Dustin Koupal <dkoupal@blizzard.com>

Closes #17554 from cooper6581/typo-daraframes.

## What changes were proposed in this pull request?

- Fixed bug in Java API not passing timeout conf to scala API
- Updated markdown docs
- Updated scala docs
- Added scala and Java example

## How was this patch tested?
Manually ran examples.

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #17539 from tdas/SPARK-20224.

## What changes were proposed in this pull request?

Add docs and examples for spark.ml.feature.Imputer. Currently scala and Java examples are included. Python example will be added after https://github.com/apache/spark/pull/17316

## How was this patch tested?

local doc generation and example execution

Author: Yuhao Yang <yuhao.yang@intel.com>

Closes #17324 from hhbyyh/imputerdoc.

…adoc

## What changes were proposed in this pull request?

Use recommended values for row boundaries in Window's scaladoc, i.e. `Window.unboundedPreceding`, `Window.unboundedFollowing`, and `Window.currentRow` (that were introduced in 2.1.0).

## How was this patch tested?

Local build

Author: Jacek Laskowski <jacek@japila.pl>

Closes #17417 from jaceklaskowski/window-expression-scaladoc.

## What changes were proposed in this pull request?

There are two examples in r folder missing the run commands.

In this PR, I just add the missing comment, which is consistent with other examples.

## How was this patch tested?

Manual test.

Author: wm624@hotmail.com <wm624@hotmail.com>

Closes #17474 from wangmiao1981/stat.

[SPARK-10849][SQL] Adds option to the JDBC data source write for user to specify database column type for the create table

## What changes were proposed in this pull request?
Currently JDBC data source creates tables in the target database using the default type mapping, and the JDBC dialect mechanism.  If users want to specify different database data type for only some of columns, there is no option available. In scenarios where default mapping does not work, users are forced to create tables on the target database before writing. This workaround is probably not acceptable from a usability point of view. This PR is to provide a user-defined type mapping for specific columns.

The solution is to allow users to specify database column data type for the create table  as JDBC datasource option(createTableColumnTypes) on write. Data type information can be specified in the same format as table schema DDL format (e.g: `name CHAR(64), comments VARCHAR(1024)`).

All supported target database types can not be specified ,  the data types has to be valid spark sql data types also.  For example user can not specify target database  CLOB data type. This will be supported in the follow-up PR.

Example:
```Scala
df.write
.option("createTableColumnTypes", "name CHAR(64), comments VARCHAR(1024)")
.jdbc(url, "TEST.DBCOLTYPETEST", properties)
```
## How was this patch tested?
Added new test cases to the JDBCWriteSuite

Author: sureshthalamati <suresh.thalamati@gmail.com>

Closes #16209 from sureshthalamati/jdbc_custom_dbtype_option_json-spark-10849.

[SPARK-14489](https://issues.apache.org/jira/browse/SPARK-14489) added the ability to skip `NaN` predictions during `ALSModel.transform`. This PR adds documentation for the `coldStartStrategy` param to the ALS user guide, and add code to the examples to illustrate usage.

## How was this patch tested?

Doc and example change only. Build HTML doc locally and verified example code builds, and runs in shell for Scala/Python.

Author: Nick Pentreath <nickp@za.ibm.com>

Closes #17102 from MLnick/SPARK-19345-coldstart-doc.

## What changes were proposed in this pull request?
Remove `org.apache.spark.examples.` in
Add slash in one of the python doc.

## How was this patch tested?
Run examples using the commands in the comments.

Author: Yun Ni <yunn@uber.com>

Closes #17104 from Yunni/yunn_minor.

[SPARK-19460][SPARKR] Update dataset used in R documentation, examples to reduce warning noise and confusions

## What changes were proposed in this pull request?

Replace `iris` dataset with `Titanic` or other dataset in example and document.

## How was this patch tested?

Manual and existing test

Author: wm624@hotmail.com <wm624@hotmail.com>

Closes #17032 from wangmiao1981/example.

## What changes were proposed in this pull request?

This PR proposes to replace the deprecated `json(RDD[String])` usage to `json(Dataset[String])`.

This currently produces so many warnings.

## How was this patch tested?

Fixed tests.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17071 from HyukjinKwon/SPARK-15615-followup.