## What changes were proposed in this pull request?
We can remove this file based on discussion at https://issues.apache.org/jira/browse/SPARK-17828 it's evident this file has been redundant for a while, JIRA release notes serves this purpose for us already.

For ease of future reference you can find detailed release notes at, for example:

http://spark.apache.org/downloads.html -> http://spark.apache.org/releases/spark-release-2-0-1.html -> "Detailed changes" which links to https://issues.apache.org/jira/secure/ReleaseNote.jspa?projectId=12315420&version=12336857

## How was this patch tested?
Searched the codebase and saw nothing referencing this, hasn't been used in a while (probably manually invoked a long time ago)

Author: Adam Roberts <aroberts@uk.ibm.com>

Closes #15419 from a-roberts/patch-7.

## What changes were proposed in this pull request?
This patch annotates the InterfaceStability level for top level classes in o.a.spark.sql and o.a.spark.sql.util packages, to experiment with this new annotation.

## How was this patch tested?
N/A

Author: Reynold Xin <rxin@databricks.com>

Closes #15392 from rxin/SPARK-17830.

## What changes were proposed in this pull request?
Currently the no. of partition files are limited to 10000 files (%05d format). If there are more than 10000 part files, the logic goes for a toss while recreating the RDD as it sorts them by string. More details can be found in the JIRA desc [here](https://issues.apache.org/jira/browse/SPARK-17417).

## How was this patch tested?
I tested this patch by checkpointing a RDD and then manually renaming part files to the old format and tried to access the RDD. It was successfully created from the old format. Also verified loading a sample parquet file and saving it as multiple formats - CSV, JSON, Text, Parquet, ORC and read them successfully back from the saved files. I couldn't launch the unit test from my local box, so will wait for the Jenkins output.

Author: Dhruve Ashar <dhruveashar@gmail.com>

Closes #15370 from dhruve/bug/SPARK-17417.

## What changes were proposed in this pull request?

The function `SparkSqlParserSuite.createTempViewUsing` is not used for now and causes build failure, this PR simply removes it.

## How was this patch tested?
N/A

Author: jiangxingbo <jiangxb1987@gmail.com>

Closes #15418 from jiangxb1987/parserSuite.

## What changes were proposed in this pull request?

Global temporary view is a cross-session temporary view, which means it's shared among all sessions. Its lifetime is the lifetime of the Spark application, i.e. it will be automatically dropped when the application terminates. It's tied to a system preserved database `global_temp`(configurable via SparkConf), and we must use the qualified name to refer a global temp view, e.g. SELECT * FROM global_temp.view1.

changes for `SessionCatalog`:

1. add a new field `gloabalTempViews: GlobalTempViewManager`, to access the shared global temp views, and the global temp db name.
2. `createDatabase` will fail if users wanna create `global_temp`, which is system preserved.
3. `setCurrentDatabase` will fail if users wanna set `global_temp`, which is system preserved.
4. add `createGlobalTempView`, which is used in `CreateViewCommand` to create global temp views.
5. add `dropGlobalTempView`, which is used in `CatalogImpl` to drop global temp view.
6. add `alterTempViewDefinition`, which is used in `AlterViewAsCommand` to update the view definition for local/global temp views.
7. `renameTable`/`dropTable`/`isTemporaryTable`/`lookupRelation`/`getTempViewOrPermanentTableMetadata`/`refreshTable` will handle global temp views.

changes for SQL commands:

1. `CreateViewCommand`/`AlterViewAsCommand` is updated to support global temp views
2. `ShowTablesCommand` outputs a new column `database`, which is used to distinguish global and local temp views.
3. other commands can also handle global temp views if they call `SessionCatalog` APIs which accepts global temp views, e.g. `DropTableCommand`, `AlterTableRenameCommand`, `ShowColumnsCommand`, etc.

changes for other public API

1. add a new method `dropGlobalTempView` in `Catalog`
2. `Catalog.findTable` can find global temp view
3. add a new method `createGlobalTempView` in `Dataset`

## How was this patch tested?

new tests in `SQLViewSuite`

Author: Wenchen Fan <wenchen@databricks.com>

Closes #14897 from cloud-fan/global-temp-view.

## What changes were proposed in this pull request?

Currently we use the same rule to parse top level and nested data fields. For example:
```
create table tbl_x(
  id bigint,
  nested struct<col1:string,col2:string>
)
```
Shows both syntaxes. In this PR we split this rule in a top-level and nested rule.

Before this PR,
```
sql("CREATE TABLE my_tab(column1: INT)")
```
works fine.
After this PR, it will throw a `ParseException`:
```
scala> sql("CREATE TABLE my_tab(column1: INT)")
org.apache.spark.sql.catalyst.parser.ParseException:
no viable alternative at input 'CREATE TABLE my_tab(column1:'(line 1, pos 27)
```

## How was this patch tested?
Add new testcases in `SparkSqlParserSuite`.

Author: jiangxingbo <jiangxb1987@gmail.com>

Closes #15346 from jiangxb1987/cdt.

[SPARK-17832][SQL] TableIdentifier.quotedString creates un-parseable names when name contains a backtick

## What changes were proposed in this pull request?

The `quotedString` method in `TableIdentifier` and `FunctionIdentifier` produce an illegal (un-parseable) name when the name contains a backtick. For example:
```
import org.apache.spark.sql.catalyst.parser.CatalystSqlParser._
import org.apache.spark.sql.catalyst.TableIdentifier
import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
val complexName = TableIdentifier("`weird`table`name", Some("`d`b`1"))
parseTableIdentifier(complexName.unquotedString) // Does not work
parseTableIdentifier(complexName.quotedString) // Does not work
parseExpression(complexName.unquotedString) // Does not work
parseExpression(complexName.quotedString) // Does not work
```
We should handle the backtick properly to make `quotedString` parseable.

## How was this patch tested?
Add new testcases in `TableIdentifierParserSuite` and `ExpressionParserSuite`.

Author: jiangxingbo <jiangxb1987@gmail.com>

Closes #15403 from jiangxb1987/backtick.

## What changes were proposed in this pull request?
This PR modified the test case `test("script")` to use resource path for `test_script.sh`. Make the test case portable (even in IntelliJ).

## How was this patch tested?
Passed the test case.
Before:
Run `test("script")` in IntelliJ:
```
Caused by: org.apache.spark.SparkException: Subprocess exited with status 127. Error: bash: src/test/resources/test_script.sh: No such file or directory
```
After:
Test passed.

Author: Weiqing Yang <yangweiqing001@gmail.com>

Closes #15246 from weiqingy/hivetest.

## What changes were proposed in this pull request?

Fix:

- GroupedMeanEvaluator and GroupedSumEvaluator are unused, as is the StudentTCacher support class
- CountEvaluator can return a lower bound < 0, when counts can't be negative
- MeanEvaluator will actually fail on exactly 1 datum (yields t-test with 0 DOF)
- CountEvaluator uses a normal distribution, which may be an inappropriate approximation (leading to above)
- Test for SumEvaluator asserts incorrect expected sums – e.g. after observing 10% of data has sum of 2, expectation should be 20, not 38
- CountEvaluator, MeanEvaluator have no unit tests to catch these
- Duplication of distribution code across CountEvaluator, GroupedCountEvaluator
- The stats in each could use a bit of documentation as I had to guess at them
- (Code could use a few cleanups and optimizations too)

## How was this patch tested?

Existing and new tests

Author: Sean Owen <sowen@cloudera.com>

Closes #15341 from srowen/SPARK-17768.

## What changes were proposed in this pull request?

Added secondary sorting on stage name for the description column. This provide a clearer behavior in the common case where the Description column only comprises of Stage names instead of the option description value.

## How was this patch tested?

manual testing and dev/run-tests

Screenshots of sorting on both description and stage name as well as an example of both:
![screen shot 2016-10-04 at 1 09 39 pm](https://cloud.githubusercontent.com/assets/13952758/19135523/067b042e-8b1a-11e6-912e-e6371d006d21.png)
![screen shot 2016-10-04 at 1 09 51 pm](https://cloud.githubusercontent.com/assets/13952758/19135526/06960936-8b1a-11e6-85e9-8aaf694c5f7b.png)
![screen shot 2016-10-05 at 1 14 45 pm](https://cloud.githubusercontent.com/assets/13952758/19135525/069547da-8b1a-11e6-8692-6524c75c4c07.png)
![screen shot 2016-10-05 at 1 14 51 pm](https://cloud.githubusercontent.com/assets/13952758/19135524/0694b4d2-8b1a-11e6-92dc-c8aa514e4f62.png)
![screen shot 2016-10-05 at 4 42 52 pm](https://cloud.githubusercontent.com/assets/13952758/19135618/e232eafe-8b1a-11e6-88b3-ff0bbb26b7f8.png)

Author: Alex Bozarth <ajbozart@us.ibm.com>

Closes #15366 from ajbozarth/spark17793.

## What changes were proposed in this pull request?
While adding R wrapper for LogisticRegression, I found one extra comment. It is minor and I just remove it.

## How was this patch tested?
Unit tests

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

Closes #15391 from wangmiao1981/mlordoc.

## What changes were proposed in this pull request?

This PR proposes the fix the use of `contains` API which only exists from Scala 2.11.

## How was this patch tested?

Manually checked:

```scala
scala> val o: Option[Boolean] = None
o: Option[Boolean] = None

scala> o == Some(false)
res17: Boolean = false

scala> val o: Option[Boolean] = Some(true)
o: Option[Boolean] = Some(true)

scala> o == Some(false)
res18: Boolean = false

scala> val o: Option[Boolean] = Some(false)
o: Option[Boolean] = Some(false)

scala> o == Some(false)
res19: Boolean = true
```

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15393 from HyukjinKwon/hotfix.

## What changes were proposed in this pull request?

In HashJoin, we try to rewrite the join key as Long to improve the performance of finding a match. The rewriting part is not well tested, has a bug that could cause wrong result when there are at least three integral columns in the joining key also the total length of the key exceed 8 bytes.

## How was this patch tested?

Added unit test to covering the rewriting with different number of columns and different data types. Manually test the reported case and confirmed that this PR fix the bug.

Author: Davies Liu <davies@databricks.com>

Closes #15390 from davies/rewrite_key.

## What changes were proposed in this pull request?
In practice we cannot guarantee that an `InternalRow` is immutable. This makes the `MutableRow` almost redundant. This PR folds `MutableRow` into `InternalRow`.

The code below illustrates the immutability issue with InternalRow:
```scala
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions.GenericMutableRow
val struct = new GenericMutableRow(1)
val row = InternalRow(struct, 1)
println(row)
scala> [[null], 1]
struct.setInt(0, 42)
println(row)
scala> [[42], 1]
```

This might be somewhat controversial, so feedback is appreciated.

## How was this patch tested?
Existing tests.

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

Closes #15333 from hvanhovell/SPARK-17761.

## What changes were proposed in this pull request?

When execute a Python UDF, we buffer the input row into as queue, then pull them out to join with the result from Python UDF. In the case that Python UDF is slow or the input row is too wide, we could ran out of memory because of the queue. Since we can't flush all the buffers (sockets) between JVM and Python process from JVM side, we can't limit the rows in the queue, otherwise it could deadlock.

This PR will manage the memory used by the queue, spill that into disk when there is no enough memory (also release the memory and disk space as soon as possible).

## How was this patch tested?

Added unit tests. Also manually ran a workload with large input row and slow python UDF (with  large broadcast) like this:

```
b = range(1<<24)
add = udf(lambda x: x + len(b), IntegerType())
df = sqlContext.range(1, 1<<26, 1, 4)
print df.select(df.id, lit("adf"*10000).alias("s"), add(df.id).alias("add")).groupBy(length("s")).sum().collect()
```

It ran out of memory (hang because of full GC) before the patch, ran smoothly after the patch.

Author: Davies Liu <davies@databricks.com>

Closes #15089 from davies/spill_udf.

## What changes were proposed in this pull request?

This PR includes the changes below:

  - Support `mode`/`options` in `read.parquet`, `write.parquet`, `read.orc`, `write.orc`, `read.text`, `write.text`, `read.json` and `write.json` APIs

  - Support other types (logical, numeric and string) as options for `write.df`, `read.df`, `read.parquet`, `write.parquet`, `read.orc`, `write.orc`, `read.text`, `write.text`, `read.json` and `write.json`

## How was this patch tested?

Unit tests in `test_sparkSQL.R`/ `utils.R`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15239 from HyukjinKwon/SPARK-17665.

## What changes were proposed in this pull request?

Adds the textFile API which exists in DataFrameReader and serves same purpose.

## How was this patch tested?

Added corresponding testcase.

Author: Prashant Sharma <prashsh1@in.ibm.com>

Closes #14087 from ScrapCodes/textFile.

## What changes were proposed in this pull request?

This PR proposes cleaning up the confusing part in `createRelation` as discussed in https://github.com/apache/spark/pull/12601/files#r80627940

Also, this PR proposes the changes below:

 - Add documentation for `batchsize` and `isolationLevel`.
 - Move property names into `JDBCOptions` so that they can be managed in a single place. which were, `fetchsize`, `batchsize`, `isolationLevel` and `driver`.

## How was this patch tested?

Existing tests should cover this.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15263 from HyukjinKwon/SPARK-14525.

## What changes were proposed in this pull request?

This expands calls to Jetty's simple `ServerConnector` constructor to explicitly specify a `ScheduledExecutorScheduler` that makes daemon threads. It should otherwise result in exactly the same configuration, because the other args are copied from the constructor that is currently called.

(I'm not sure we should change the Hive Thriftserver impl, but I did anyway.)

This also adds `sc.stop()` to the quick start guide example.

## How was this patch tested?

Existing tests; _pending_ at least manual verification of the fix.

Author: Sean Owen <sowen@cloudera.com>

Closes #15381 from srowen/SPARK-17707.

## What changes were proposed in this pull request?
This patch introduces three new annotations under InterfaceStability:
- Stable
- Evolving
- Unstable

This is inspired by Hadoop's InterfaceStability, and the first step towards switching over to a new API stability annotation framework.

## How was this patch tested?
N/A

Author: Reynold Xin <rxin@databricks.com>

Closes #15374 from rxin/SPARK-17800.

## What changes were proposed in this pull request?

Fix a bug where spill metrics were being reported as shuffle metrics. Eventually these spill metrics should be reported (SPARK-3577), but separate from shuffle metrics. The fix itself basically reverts the line to what it was in 1.6.

## How was this patch tested?

Tested on a job that was reporting shuffle writes even for the final stage, when no shuffle writes should take place. After the change the job no longer shows these writes.

Before:
![screen shot 2016-10-03 at 6 39 59 pm](https://cloud.githubusercontent.com/assets/1514239/19085897/dbf59a92-8a20-11e6-9f68-a978860c0d74.png)

After:
<img width="1052" alt="screen shot 2016-10-03 at 11 44 44 pm" src="https://cloud.githubusercontent.com/assets/1514239/19085903/e173a860-8a20-11e6-85e3-d47f9835f494.png">

Author: Brian Cho <bcho@fb.com>

Closes #15347 from dafrista/shuffle-metrics.

[SPARK-16960][SQL] Deprecate approxCountDistinct, toDegrees and toRadians according to FunctionRegistry

## What changes were proposed in this pull request?

It seems `approxCountDistinct`, `toDegrees` and `toRadians` are also missed while matching the names to the ones in `FunctionRegistry`. (please see [approx_count_distinct](https://github.com/apache/spark/blob/5c2ae79bfcf448d8dc9217efafa1409997c739de/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala#L244), [degrees](https://github.com/apache/spark/blob/5c2ae79bfcf448d8dc9217efafa1409997c739de/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala#L203) and [radians](https://github.com/apache/spark/blob/5c2ae79bfcf448d8dc9217efafa1409997c739de/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala#L222) in `FunctionRegistry`).

I took a scan between `functions.scala` and `FunctionRegistry` and it seems these are all left. For `countDistinct` and `sumDistinct`, they are not registered in `FunctionRegistry`.

This PR deprecates `approxCountDistinct`, `toDegrees` and `toRadians` and introduces `approx_count_distinct`, `degrees` and `radians`.

## How was this patch tested?

Existing tests should cover this.

Author: hyukjinkwon <gurwls223@gmail.com>
Author: Hyukjin Kwon <gurwls223@gmail.com>

Closes #14538 from HyukjinKwon/SPARK-16588-followup.

## What changes were proposed in this pull request?

Added anchor on table header id to sorting links on job and stage tables. This make the page reload after a sort load the page at the sorted table.

This only changes page load behavior so no UI changes

## How was this patch tested?

manually tested and dev/run-tests

Author: Alex Bozarth <ajbozart@us.ibm.com>

Closes #15369 from ajbozarth/spark17795.

## What changes were proposed in this pull request?
This PR adds the Kafka 0.10 subproject to the build infrastructure. This makes sure Kafka 0.10 tests are only triggers when it or of its dependencies change.

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

Closes #15355 from hvanhovell/SPARK-17782.

## What changes were proposed in this pull request?
If given a list of paths, `pyspark.sql.readwriter.text` will attempt to use an undefined variable `paths`.  This change checks if the param `paths` is a basestring and then converts it to a list, so that the same variable `paths` can be used for both cases

## How was this patch tested?
Added unit test for reading list of files

Author: Bryan Cutler <cutlerb@gmail.com>

Closes #15379 from BryanCutler/sql-readtext-paths-SPARK-17805.

[SPARK-17792][ML] L-BFGS solver for linear regression does not accept general numeric label column types

## What changes were proposed in this pull request?

Before, we computed `instances` in LinearRegression in two spots, even though they did the same thing. One of them did not cast the label column to `DoubleType`. This patch consolidates the computation and always casts the label column to `DoubleType`.

## How was this patch tested?

Added a unit test to check all solvers. This test failed before this patch.

Author: sethah <seth.hendrickson16@gmail.com>

Closes #15364 from sethah/linreg_numeric_type.

[SPARK-17803: Docker integration tests don't run with "Docker for Mac"](https://issues.apache.org/jira/browse/SPARK-17803)

## What changes were proposed in this pull request?

This PR upgrades the [docker-client](https://mvnrepository.com/artifact/com.spotify/docker-client) dependency from [3.6.6](https://mvnrepository.com/artifact/com.spotify/docker-client/3.6.6) to [5.0.2](https://mvnrepository.com/artifact/com.spotify/docker-client/5.0.2) to enable _Docker for Mac_ users to run the `docker-integration-tests` out of the box.

The very latest docker-client version is [6.0.0](https://mvnrepository.com/artifact/com.spotify/docker-client/6.0.0) but that has one additional dependency and no usage yet.

## How was this patch tested?

The code change was tested on Mac OS X Yosemite with both _Docker Toolbox_ as well as _Docker for Mac_ and on Linux Ubuntu 14.04.

```
$ build/mvn -Pyarn -Phadoop-2.6 -Dhadoop.version=2.6.0 -Phive -Phive-thriftserver -DskipTests clean package

$ build/mvn -Pdocker-integration-tests -Pscala-2.11 -pl :spark-docker-integration-tests_2.11 clean compile test
```

Author: Christian Kadner <ckadner@us.ibm.com>

Closes #15378 from ckadner/SPARK-17803_Docker_for_Mac.

## What changes were proposed in this pull request?

When using an incompatible source for structured streaming, it may throw NoClassDefFoundError. It's better to just catch Throwable and report it to the user since the streaming thread is dying.

## How was this patch tested?

`test("NoClassDefFoundError from an incompatible source")`

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #15352 from zsxwing/SPARK-17780.

## What changes were proposed in this pull request?
I was looking through API annotations to catch mislabeled APIs, and realized DataStreamReader and DataStreamWriter classes are already annotated as Experimental, and as a result there is no need to annotate each method within them.

## How was this patch tested?
N/A

Author: Reynold Xin <rxin@databricks.com>

Closes #15373 from rxin/SPARK-17798.

## What changes were proposed in this pull request?

Currently, Spark raises `RuntimeException` when creating a view with timestamp with INTERVAL arithmetic like the following. The root cause is the arithmetic expression, `TimeAdd`, was transformed into `timeadd` function as a VIEW definition. This PR fixes the SQL definition of `TimeAdd` and `TimeSub` expressions.

```scala
scala> sql("CREATE TABLE dates (ts TIMESTAMP)")

scala> sql("CREATE VIEW view1 AS SELECT ts + INTERVAL 1 DAY FROM dates")
java.lang.RuntimeException: Failed to analyze the canonicalized SQL: ...
```

## How was this patch tested?

Pass Jenkins with a new testcase.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #15318 from dongjoon-hyun/SPARK-17750.

## What changes were proposed in this pull request?

This PR proposes to close some stale PRs and ones suggested to be closed by committer(s) or obviously inappropriate PRs (e.g. branch to branch).

Closes #13458
Closes #15278
Closes #15294
Closes #15339
Closes #15283

## How was this patch tested?

N/A

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15356 from HyukjinKwon/closing-prs.

## What changes were proposed in this pull request?
Avoid 2D array flatten in ```NaiveBayes``` training, since flatten method might be expensive (It will create another array and copy data there).

## How was this patch tested?
Existing tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #15359 from yanboliang/nb-theta.

## What changes were proposed in this pull request?

Generate the sql test jar to fix the maven build

## How was this patch tested?

Jenkins

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #15368 from zsxwing/sql-test-jar.

## What changes were proposed in this pull request?

This PR adds a new project ` external/kafka-0-10-sql` for Structured Streaming Kafka source.

It's based on the design doc: https://docs.google.com/document/d/19t2rWe51x7tq2e5AOfrsM9qb8_m7BRuv9fel9i0PqR8/edit?usp=sharing

tdas did most of work and part of them was inspired by koeninger's work.

### Introduction

The Kafka source is a structured streaming data source to poll data from Kafka. The schema of reading data is as follows:

Column | Type
---- | ----
key | binary
value | binary
topic | string
partition | int
offset | long
timestamp | long
timestampType | int

The source can deal with deleting topics. However, the user should make sure there is no Spark job processing the data when deleting a topic.

### Configuration

The user can use `DataStreamReader.option` to set the following configurations.

Kafka Source's options | value | default | meaning
------ | ------- | ------ | -----
startingOffset | ["earliest", "latest"] | "latest" | The start point when a query is started, either "earliest" which is from the earliest offset, or "latest" which is just from the latest offset. Note: This only applies when a new Streaming query is started, and that resuming will always pick up from where the query left off.
failOnDataLost | [true, false] | true | Whether to fail the query when it's possible that data is lost (e.g., topics are deleted, or offsets are out of range). This may be a false alarm. You can disable it when it doesn't work as you expected.
subscribe | A comma-separated list of topics | (none) | The topic list to subscribe. Only one of "subscribe" and "subscribeParttern" options can be specified for Kafka source.
subscribePattern | Java regex string | (none) | The pattern used to subscribe the topic. Only one of "subscribe" and "subscribeParttern" options can be specified for Kafka source.
kafka.consumer.poll.timeoutMs | long | 512 | The timeout in milliseconds to poll data from Kafka in executors
fetchOffset.numRetries | int | 3 | Number of times to retry before giving up fatch Kafka latest offsets.
fetchOffset.retryIntervalMs | long | 10 | milliseconds to wait before retrying to fetch Kafka offsets

Kafka's own configurations can be set via `DataStreamReader.option` with `kafka.` prefix, e.g, `stream.option("kafka.bootstrap.servers", "host:port")`

### Usage

* Subscribe to 1 topic
```Scala
spark
  .readStream
  .format("kafka")
  .option("kafka.bootstrap.servers", "host:port")
  .option("subscribe", "topic1")
  .load()
```

* Subscribe to multiple topics
```Scala
spark
  .readStream
  .format("kafka")
  .option("kafka.bootstrap.servers", "host:port")
  .option("subscribe", "topic1,topic2")
  .load()
```

* Subscribe to a pattern
```Scala
spark
  .readStream
  .format("kafka")
  .option("kafka.bootstrap.servers", "host:port")
  .option("subscribePattern", "topic.*")
  .load()
```

## How was this patch tested?

The new unit tests.

Author: Shixiong Zhu <shixiong@databricks.com>
Author: Tathagata Das <tathagata.das1565@gmail.com>
Author: Shixiong Zhu <zsxwing@gmail.com>
Author: cody koeninger <cody@koeninger.org>

Closes #15102 from zsxwing/kafka-source.

## What changes were proposed in this pull request?
The result of the `Last` function can be wrong when the last partition processed is empty. It can return `null` instead of the expected value. For example, this can happen when we process partitions in the following order:
```
- Partition 1 [Row1, Row2]
- Partition 2 [Row3]
- Partition 3 []
```
In this case the `Last` function will currently return a null, instead of the value of `Row3`.

This PR fixes this by adding a `valueSet` flag to the `Last` function.

## How was this patch tested?
We only used end to end tests for `DeclarativeAggregateFunction`s. I have added an evaluator for these functions so we can tests them in catalyst. I have added a `LastTestSuite` to test the `Last` aggregate function.

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

Closes #15348 from hvanhovell/SPARK-17758.

## What changes were proposed in this pull request?

Mock SparkContext to reduce memory usage of BlockManagerSuite

## How was this patch tested?

Jenkins

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #15350 from zsxwing/SPARK-17778.

## What changes were proposed in this pull request?
Updates user guide to reflect that LogisticRegression now supports multiclass. Also adds new examples to show multiclass training.

## How was this patch tested?
Ran locally using spark-submit, run-example, and copy/paste from user guide into shells. Generated docs and verified correct output.

Author: sethah <seth.hendrickson16@gmail.com>

Closes #15349 from sethah/SPARK-17239.

## What changes were proposed in this pull request?

This PR fixes the following NPE scenario in two ways.

**Reported Error Scenario**
```scala
scala> sql("EXPLAIN DESCRIBE TABLE x").show(truncate = false)
INFO SparkSqlParser: Parsing command: EXPLAIN DESCRIBE TABLE x
java.lang.NullPointerException
```

- **DESCRIBE**: Extend `DESCRIBE` syntax to accept `TABLE`.
- **EXPLAIN**: Prevent NPE in case of the parsing failure of target statement, e.g., `EXPLAIN DESCRIBE TABLES x`.

## How was this patch tested?

Pass the Jenkins test with a new test case.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #15357 from dongjoon-hyun/SPARK-17328.

## What changes were proposed in this pull request?
Currently Spark SQL parses regular decimal literals (e.g. `10.00`) as decimals and scientific decimal literals (e.g. `10.0e10`) as doubles. The difference between the two confuses most users. This PR unifies the parsing behavior and also parses scientific decimal literals as decimals.

This implications in tests are limited to a single Hive compatibility test.

## How was this patch tested?
Updated tests in `ExpressionParserSuite` and `SQLQueryTestSuite`.

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

Closes #14828 from hvanhovell/SPARK-17258.

## What changes were proposed in this pull request?

`write.df`/`read.df` API require path which is not actually always necessary in Spark. Currently, it only affects the datasources implementing `CreatableRelationProvider`. Currently, Spark currently does not have internal data sources implementing this but it'd affect other external datasources.

In addition we'd be able to use this way in Spark's JDBC datasource after https://github.com/apache/spark/pull/12601 is merged.

**Before**

 - `read.df`

  ```r
> read.df(source = "json")
Error in dispatchFunc("read.df(path = NULL, source = NULL, schema = NULL, ...)",  :
  argument "x" is missing with no default
```

  ```r
> read.df(path = c(1, 2))
Error in dispatchFunc("read.df(path = NULL, source = NULL, schema = NULL, ...)",  :
  argument "x" is missing with no default
```

  ```r
> read.df(c(1, 2))
Error in invokeJava(isStatic = TRUE, className, methodName, ...) :
  java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.String
	at org.apache.spark.sql.execution.datasources.DataSource.hasMetadata(DataSource.scala:300)
	at
...
In if (is.na(object)) { :
...
```

 - `write.df`

  ```r
> write.df(df, source = "json")
Error in (function (classes, fdef, mtable)  :
  unable to find an inherited method for function ‘write.df’ for signature ‘"function", "missing"’
```

  ```r
> write.df(df, source = c(1, 2))
Error in (function (classes, fdef, mtable)  :
  unable to find an inherited method for function ‘write.df’ for signature ‘"SparkDataFrame", "missing"’
```

  ```r
> write.df(df, mode = TRUE)
Error in (function (classes, fdef, mtable)  :
  unable to find an inherited method for function ‘write.df’ for signature ‘"SparkDataFrame", "missing"’
```

**After**

- `read.df`

  ```r
> read.df(source = "json")
Error in loadDF : analysis error - Unable to infer schema for JSON at . It must be specified manually;
```

  ```r
> read.df(path = c(1, 2))
Error in f(x, ...) : path should be charactor, null or omitted.
```

  ```r
> read.df(c(1, 2))
Error in f(x, ...) : path should be charactor, null or omitted.
```

- `write.df`

  ```r
> write.df(df, source = "json")
Error in save : illegal argument - 'path' is not specified
```

  ```r
> write.df(df, source = c(1, 2))
Error in .local(df, path, ...) :
  source should be charactor, null or omitted. It is 'parquet' by default.
```

  ```r
> write.df(df, mode = TRUE)
Error in .local(df, path, ...) :
  mode should be charactor or omitted. It is 'error' by default.
```

## How was this patch tested?

Unit tests in `test_sparkSQL.R`

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15231 from HyukjinKwon/write-default-r.