[SPARK-3279] Remove useless field variable in ApplicationMaster

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2177 from sarutak/SPARK-3279 and squashes the following commits:

2955edc [Kousuke Saruta] Removed useless field variable from ApplicationMaster
[SPARK-3307] [PySpark] Fix doc string of SparkContext.broadcast()

 remove invalid docs

Author: Davies Liu <davies.liu@gmail.com>

Closes #2202 from davies/keep and squashes the following commits:

aa3b44f [Davies Liu] remove invalid docs
[Docs] SQL doc formatting and typo fixes

As [reported on the dev list](http://apache-spark-developers-list.1001551.n3.nabble.com/VOTE-Release-Apache-Spark-1-1-0-RC2-tp8107p8131.html):
* Code fencing with triple-backticks doesn’t seem to work like it does on GitHub. Newlines are lost. Instead, use 4-space indent to format small code blocks.
* Nested bullets need 2 leading spaces, not 1.
* Spellcheck!

Author: Nicholas Chammas <nicholas.chammas@gmail.com>
Author: nchammas <nicholas.chammas@gmail.com>

Closes #2201 from nchammas/sql-doc-fixes and squashes the following commits:

873f889 [Nicholas Chammas] [Docs] fix skip-api flag
5195e0c [Nicholas Chammas] [Docs] SQL doc formatting and typo fixes
3b26c8d [nchammas] [Spark QA] Link to console output on test time out
SPARK-2813:  [SQL] Implement SQRT() directly in Spark SQL

This PR adds a native implementation for SQL SQRT() and thus avoids delegating this function to Hive.

Author: William Benton <willb@redhat.com>

Closes #1750 from willb/spark-2813 and squashes the following commits:

22c8a79 [William Benton] Fixed missed newline from rebase
d673861 [William Benton] Added string coercions for SQRT and associated test case
e125df4 [William Benton] Added ExpressionEvaluationSuite test cases for SQRT
7b84bcd [William Benton] SQL SQRT now properly returns NULL for NULL inputs
8256971 [William Benton] added SQRT test to SqlQuerySuite
504d2e5 [William Benton] Added native SQRT implementation
[SPARK-3234][Build] Fixed environment variables that rely on deprecated command line options in make-distribution.sh

Please refer to [SPARK-3234](https://issues.apache.org/jira/browse/SPARK-3234) for details.

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

Closes #2208 from liancheng/spark-3234 and squashes the following commits:

fb26de8 [Cheng Lian] Fixed SPARK-3234
[SPARK-3198] [SQL] Remove the TreeNode.id

Thus id property of the TreeNode API does save time in a faster way to compare 2 TreeNodes, it is kind of performance bottleneck during the expression object creation in a multi-threading env (because of the memory barrier).
Fortunately, the tree node comparison only happen once in master, so even we remove it, the entire performance will not be affected.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #2155 from chenghao-intel/treenode and squashes the following commits:

7cf2cd2 [Cheng Hao] Remove the implicit keyword for TreeNodeRef and some other small issues
5873415 [Cheng Hao] Remove the TreeNode.id
[SQL] Turns on in-memory columnar compression in HiveCompatibilitySuite

`HiveCompatibilitySuite` already turns on in-memory columnar caching, it would be good to also enable compression to improve test coverage.

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

Closes #2190 from liancheng/compression-on and squashes the following commits:

88b536c [Cheng Lian] Code cleanup, narrowed field visibility
d13efd2 [Cheng Lian] Turns on in-memory columnar compression in HiveCompatibilitySuite
[SPARK-3269][SQL] Decreases initial buffer size for row set to prevent OOM

When a large batch size is specified, `SparkSQLOperationManager` OOMs even if the whole result set is much smaller than the batch size.

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

Closes #2171 from liancheng/jdbc-fetch-size and squashes the following commits:

5e1623b [Cheng Lian] Decreases initial buffer size for row set to prevent OOM
[SPARK-3291][SQL]TestcaseName in createQueryTest should not contain ":"

":" is not allowed to appear in a file name of Windows system. If file name contains ":", this file can't be checked out in a Windows system and developers using Windows must be careful to not commit the deletion of such files, Which is very inconvenient.

Author: qiping.lqp <qiping.lqp@alibaba-inc.com>

Closes #2191 from chouqin/querytest and squashes the following commits:

0e943a1 [qiping.lqp] rename golden file
60a863f [qiping.lqp] TestcaseName in createQueryTest should not contain ":"
 [SPARK-3173][SQL] Timestamp support in the parser

If you have a table with TIMESTAMP column, that column can't be used in WHERE clause properly - it is not evaluated properly. [More](https://issues.apache.org/jira/browse/SPARK-3173)

Motivation: http://www.aproint.com/aggregation-with-spark-sql/

- [x] modify SqlParser so it supports casting to TIMESTAMP (workaround for item 2)
- [x] the string literal should be converted into Timestamp if the column is Timestamp.

Author: Zdenek Farana <zdenek.farana@gmail.com>
Author: Zdenek Farana <zdenek.farana@aproint.com>

Closes #2084 from byF/SPARK-3173 and squashes the following commits:

442b59d [Zdenek Farana] Fixed test merge conflict
2dbf4f6 [Zdenek Farana] Merge remote-tracking branch 'origin/SPARK-3173' into SPARK-3173
65b6215 [Zdenek Farana] Fixed timezone sensitivity in the test
47b27b4 [Zdenek Farana] Now works in the case of "StringLiteral=TimestampColumn"
96a661b [Zdenek Farana] Code style change
491dfcf [Zdenek Farana] Added test cases for SPARK-3173
4446b1e [Zdenek Farana] A string literal is casted into Timestamp when the column is Timestamp.
59af397 [Zdenek Farana] Added a new TIMESTAMP keyword; CAST to TIMESTAMP now can be used in SQL expression.
[SPARK-3296][mllib] spark-example should be run-example in head notation of DenseKMeans and SparseNaiveBayes

`./bin/spark-example`  should be `./bin/run-example` in DenseKMeans and SparseNaiveBayes

Author: wangfei <wangfei_hello@126.com>

Closes #2193 from scwf/run-example and squashes the following commits:

207eb3a [wangfei] spark-example should be run-example
27a8999 [wangfei] ./bin/spark-example should be ./bin/run-example
[SPARK-3320][SQL] Made batched in-memory column buffer building work for SchemaRDDs with empty partitions

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

Closes #2213 from liancheng/spark-3320 and squashes the following commits:

45a0139 [Cheng Lian] Fixed typo in InMemoryColumnarQuerySuite
f67067d [Cheng Lian] Fixed SPARK-3320