[SPARK-3161][MLLIB] Adding a node Id caching mechanism for training deci...

...sion trees. jkbradley mengxr chouqin Please review this.

Author: Sung Chung <schung@alpinenow.com>

Closes #2868 from codedeft/SPARK-3161 and squashes the following commits:

5f5a156 [Sung Chung] [SPARK-3161][MLLIB] Adding a node Id caching mechanism for training decision trees.
[SPARK-3930] [SPARK-3933] Support fixed-precision decimal in SQL, and some optimizations

- Adds optional precision and scale to Spark SQL's decimal type, which behave similarly to those in Hive 13 (https://cwiki.apache.org/confluence/download/attachments/27362075/Hive_Decimal_Precision_Scale_Support.pdf)
- Replaces our internal representation of decimals with a Decimal class that can store small values in a mutable Long, saving memory in this situation and letting some operations happen directly on Longs

This is still marked WIP because there are a few TODOs, but I'll remove that tag when done.

Author: Matei Zaharia <matei@databricks.com>

Closes #2983 from mateiz/decimal-1 and squashes the following commits:

35e6b02 [Matei Zaharia] Fix issues after merge
227f24a [Matei Zaharia] Review comments
31f915e [Matei Zaharia] Implement Davies's suggestions in Python
eb84820 [Matei Zaharia] Support reading/writing decimals as fixed-length binary in Parquet
4dc6bae [Matei Zaharia] Fix decimal support in PySpark
d1d9d68 [Matei Zaharia] Fix compile error and test issues after rebase
b28933d [Matei Zaharia] Support decimal precision/scale in Hive metastore
2118c0d [Matei Zaharia] Some test and bug fixes
81db9cb [Matei Zaharia] Added mutable Decimal that will be more efficient for small precisions
7af0c3b [Matei Zaharia] Add optional precision and scale to DecimalType, but use Unlimited for now
ec0a947 [Matei Zaharia] Make the result of AVG on Decimals be Decimal, not Double
[SPARK-3466] Limit size of results that a driver collects for each action

Right now, operations like collect() and take() can crash the driver with an OOM if they bring back too many data.

This PR will introduce spark.driver.maxResultSize, after setting it, the driver will abort a job if its result is bigger than it.

By default, it's 1g (for backward compatibility for most the cases).

In local mode, the driver and executor share the same JVM, the default setting can not protect JVM from OOM.

cc mateiz

Author: Davies Liu <davies@databricks.com>

Closes #3003 from davies/collect and squashes the following commits:

248ed5e [Davies Liu] fix compile
272522e [Davies Liu] address comments
2c35773 [Davies Liu] add sizes in message of abort()
5d62303 [Davies Liu] address comments
bc3c077 [Davies Liu] Merge branch 'master' of github.com:apache/spark into collect
11f97c5 [Davies Liu] address comments
47b144f [Davies Liu] check the size of result before send and fetch
3d81af2 [Davies Liu] address comments
ca8267d [Davies Liu] limit the size of data by collect
[SPARK-4166][Core][WebUI] Display the executor ID in the Web UI when ExecutorLostFailure happens

Now when ExecutorLostFailure happens, it only displays `ExecutorLostFailure (executor lost)`. Adding the executor id will help locate the faulted executor.

Author: zsxwing <zsxwing@gmail.com>

Closes #3033 from zsxwing/SPARK-4166 and squashes the following commits:

ff4664c [zsxwing] Backward-compatible support
c5c4cf2 [zsxwing] Display the executor ID in the Web UI when ExecutorLostFailure happens
[HOTFIX][SQL] hive test missing some golden files

cc marmbrus

Author: wangfei <wangfei1@huawei.com>

Closes #3055 from scwf/hotfix and squashes the following commits:

d881bd7 [wangfei] miss golden files
[SPARK-3247][SQL] An API for adding data sources to Spark SQL

This PR introduces a new set of APIs to Spark SQL to allow other developers to add support for reading data from new sources in `org.apache.spark.sql.sources`.

New sources must implement the interface `BaseRelation`, which is responsible for describing the schema of the data.  BaseRelations have three `Scan` subclasses, which are responsible for producing an RDD containing row objects.  The [various Scan interfaces](https://github.com/marmbrus/spark/blob/foreign/sql/core/src/main/scala/org/apache/spark/sql/sources/package.scala#L50) allow for optimizations such as column pruning and filter push down, when the underlying data source can handle these operations.

By implementing a class that inherits from RelationProvider these data sources can be accessed using using pure SQL.  I've used the functionality to update the JSON support so it can now be used in this way as follows:

```sql
CREATE TEMPORARY TABLE jsonTableSQL
USING org.apache.spark.sql.json
OPTIONS (
  path '/home/michael/data.json'
)
```

Further example usage can be found in the test cases: https://github.com/marmbrus/spark/tree/foreign/sql/core/src/test/scala/org/apache/spark/sql/sources

There is also a library that uses this new API to read avro data available here:
https://github.com/marmbrus/sql-avro

Author: Michael Armbrust <michael@databricks.com>

Closes #2475 from marmbrus/foreign and squashes the following commits:

1ed6010 [Michael Armbrust] Merge remote-tracking branch 'origin/master' into foreign
ab2c31f [Michael Armbrust] fix test
1d41bb5 [Michael Armbrust] unify argument names
5b47901 [Michael Armbrust] Remove sealed, more filter types
fab154a [Michael Armbrust] Merge remote-tracking branch 'origin/master' into foreign
e3e690e [Michael Armbrust] Add hook for extraStrategies
a70d602 [Michael Armbrust] Fix style, more tests, FilteredSuite => PrunedFilteredSuite
70da6d9 [Michael Armbrust] Modify API to ease binary compatibility and interop with Java
7d948ae [Michael Armbrust] Fix equality of AttributeReference.
5545491 [Michael Armbrust] Address comments
5031ac3 [Michael Armbrust] Merge remote-tracking branch 'origin/master' into foreign
22963ef [Michael Armbrust] package objects compile wierdly...
b069146 [Michael Armbrust] traits => abstract classes
34f836a [Michael Armbrust] Make @DeveloperApi
0d74bcf [Michael Armbrust] Add documention on object life cycle
3e06776 [Michael Armbrust] remove line wraps
de3b68c [Michael Armbrust] Remove empty file
360cb30 [Michael Armbrust] style and java api
2957875 [Michael Armbrust] add override
0fd3a07 [Michael Armbrust] Draft of data sources API
[SPARK-4182][SQL] Fixes ColumnStats classes for boolean, binary and complex data types

`NoopColumnStats` was once used for binary, boolean and complex data types. This `ColumnStats` doesn't return properly shaped column statistics and causes caching failure if a table contains columns of the aforementioned types.

This PR adds `BooleanColumnStats`, `BinaryColumnStats` and `GenericColumnStats`, used for boolean, binary and all complex data types respectively. In addition, `NoopColumnStats` returns properly shaped column statistics containing null count and row count, but this class is now used for testing purpose only.

Author: Cheng Lian <lian@databricks.com>

Closes #3059 from liancheng/spark-4182 and squashes the following commits:

b398cfd [Cheng Lian] Fixes failed test case
fb3ee85 [Cheng Lian] Fixes SPARK-4182
[SQL] Fixes race condition in CliSuite

`CliSuite` has been flaky for a while, this PR tries to improve this situation by fixing a race condition in `CliSuite`. The `captureOutput` function is used to capture both stdout and stderr output of the forked external process in two background threads and search for expected strings, but wasn't been properly synchronized before.

Author: Cheng Lian <lian@databricks.com>

Closes #3060 from liancheng/fix-cli-suite and squashes the following commits:

a70569c [Cheng Lian] Fixes race condition in CliSuite
[SPARK-3791][SQL] Provides Spark version and Hive version in HiveThriftServer2

This PR overrides the `GetInfo` Hive Thrift API to provide correct version information. Another property `spark.sql.hive.version` is added to reveal the underlying Hive version. These are generally useful for Spark SQL ODBC driver providers. The Spark version information is extracted from the jar manifest. Also took the chance to remove the `SET -v` hack, which was a workaround for Simba ODBC driver connectivity.

TODO

- [x] Find a general way to figure out Hive (or even any dependency) version.

  This [blog post](http://blog.soebes.de/blog/2014/01/02/version-information-into-your-appas-with-maven/) suggests several methods to inspect application version. In the case of Spark, this can be tricky because the chosen method:

  1. must applies to both Maven build and SBT build

    For Maven builds, we can retrieve the version information from the META-INF/maven directory within the assembly jar. But this doesn't work for SBT builds.

  2. must not rely on the original jars of dependencies to extract specific dependency version, because Spark uses assembly jar.

    This implies we can't read Hive version from Hive jar files since standard Spark distribution doesn't include them.

  3. should play well with `SPARK_PREPEND_CLASSES` to ease local testing during development.

     `SPARK_PREPEND_CLASSES` prevents classes to be loaded from the assembly jar, thus we can't locate the jar file and read its manifest.

  Given these, maybe the only reliable method is to generate a source file containing version information at build time. pwendell Do you have any suggestions from the perspective of the build process?

**Update** Hive version is now retrieved from the newly introduced `HiveShim` object.

Author: Cheng Lian <lian.cs.zju@gmail.com>
Author: Cheng Lian <lian@databricks.com>

Closes #2843 from liancheng/get-info and squashes the following commits:

a873d0f [Cheng Lian] Updates test case
53f43cd [Cheng Lian] Retrieves underlying Hive verson via HiveShim
1d282b8 [Cheng Lian] Removes the Simba ODBC "SET -v" hack
f857fce [Cheng Lian] Overrides Hive GetInfo Thrift API and adds Hive version property
[SPARK-4191][SQL]move wrapperFor to HiveInspectors to reuse it

Move wrapperFor in InsertIntoHiveTable to HiveInspectors to reuse them, this method can be reused when writing date with ObjectInspector(such as orc support)

Author: wangfei <wangfei1@huawei.com>
Author: scwf <wangfei1@huawei.com>

Closes #3057 from scwf/reuse-wraperfor and squashes the following commits:

7ccf932 [scwf] fix conflicts
d44f4da [wangfei] fix imports
9bf1b50 [wangfei] revert no related change
9a5276a [wangfei] move wrapfor to hiveinspector to reuse them
[SPARK-4185][SQL] JSON schema inference failed when dealing with type conflicts in arrays

JIRA: https://issues.apache.org/jira/browse/SPARK-4185.

This PR also has the fix of #3052.

Author: Yin Huai <huai@cse.ohio-state.edu>

Closes #3056 from yhuai/SPARK-4185 and squashes the following commits:

ed3a5a8 [Yin Huai] Correctly handle type conflicts between structs and primitive types in an array.
[SPARK-2189][SQL] Adds dropTempTable API

This PR adds an API for unregistering temporary tables. If a temporary table has been cached before, it's unpersisted as well.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #3039 from liancheng/unregister-temp-table and squashes the following commits:

54ae99f [Cheng Lian] Fixes Scala styling issue
1948c14 [Cheng Lian] Removes the unpersist argument
aca41d3 [Cheng Lian] Ensures thread safety
7d4fb2b [Cheng Lian] Adds unregisterTempTable API
[SPARK-4183] Close transport-related resources between SparkContexts

A leak of event loops may be causing test failures.

Author: Aaron Davidson <aaron@databricks.com>

Closes #3053 from aarondav/leak and squashes the following commits:

e676d18 [Aaron Davidson] Typo!
8f96475 [Aaron Davidson] Keep original ssc semantics
7e49f10 [Aaron Davidson] A leak of event loops may be causing test failures.