[SPARK-2535][SQL] Add StringComparison case to NullPropagation.

`StringComparison` expressions including `null` literal cases could be added to `NullPropagation`.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #1451 from ueshin/issues/SPARK-2535 and squashes the following commits:

e99c237 [Takuya UESHIN] Add some tests.
8f9b984 [Takuya UESHIN] Add StringComparison case to NullPropagation.
[SPARK-2540] [SQL] Add HiveDecimal & HiveVarchar support in unwrapping data

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

Closes #1436 from chenghao-intel/unwrapdata and squashes the following commits:

34cc21a [Cheng Hao] update the table scan accodringly since the unwrapData function changed
afc39da [Cheng Hao] Polish the code
39d6475 [Cheng Hao] Add HiveDecimal & HiveVarchar support in unwrap data
[SPARK-2571] Correctly report shuffle read metrics.

Currently, shuffle read metrics are incorrectly reported when stages have multiple shuffle dependencies (they are set to be the metrics from just one of the shuffle dependencies, rather than the accumulated metrics from all of the shuffle dependencies).  This fixes that problem, and should probably be back-ported to the 0.9 branch.

Thanks ryanra for discovering this problem!

cc rxin andrewor14

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #1476 from kayousterhout/join_bug and squashes the following commits:

0203a16 [Kay Ousterhout] Fix broken unit tests.
f463c2e [Kay Ousterhout] [SPARK-2571] Correctly report shuffle read metrics.
[SPARK-2359][MLlib] Correlations

Implementation for Pearson and Spearman's correlation.

Author: Doris Xin <doris.s.xin@gmail.com>

Closes #1367 from dorx/correlation and squashes the following commits:

c0dd7dc [Doris Xin] here we go
32d83a3 [Doris Xin] Reviewer comments
4db0da1 [Doris Xin] added private[stat] to Spearman
b716f70 [Doris Xin] minor fixes
6e1b42a [Doris Xin] More comments addressed. Still some open questions
8104f44 [Doris Xin] addressed comments. some open questions still
39387c2 [Doris Xin] added missing header
bd3cf19 [Doris Xin] Merge branch 'master' into correlation
6341884 [Doris Xin] race condition bug squished
bd2bacf [Doris Xin] Race condition bug
b775ff9 [Doris Xin] old wrong impl
534ebf2 [Doris Xin] Merge branch 'master' into correlation
818fa31 [Doris Xin] wip units
9d808ee [Doris Xin] wip units
b843a13 [Doris Xin] revert change in stat counter
28561b6 [Doris Xin] wip
bb2e977 [Doris Xin] minor fix
8e02c63 [Doris Xin] Merge branch 'master' into correlation
2a40aa1 [Doris Xin] initial, untested implementation of Pearson
dfc4854 [Doris Xin] WIP
[SPARK-2521] Broadcast RDD object (instead of sending it along with every task).

Currently (as of Spark 1.0.1), Spark sends RDD object (which contains closures) using Akka along with the task itself to the executors. This is inefficient because all tasks in the same stage use the same RDD object, but we have to send RDD object multiple times to the executors. This is especially bad when a closure references some variable that is very large. The current design led to users having to explicitly broadcast large variables.

The patch uses broadcast to send RDD objects and the closures to executors, and use Akka to only send a reference to the broadcast RDD/closure along with the partition specific information for the task. For those of you who know more about the internals, Spark already relies on broadcast to send the Hadoop JobConf every time it uses the Hadoop input, because the JobConf is large.

The user-facing impact of the change include:

1. Users won't need to decide what to broadcast anymore, unless they would want to use a large object multiple times in different operations
2. Task size will get smaller, resulting in faster scheduling and higher task dispatch throughput.

In addition, the change will simplify some internals of Spark, eliminating the need to maintain task caches and the complex logic to broadcast JobConf (which also led to a deadlock recently).

A simple way to test this:
```scala
val a = new Array[Byte](1000*1000); scala.util.Random.nextBytes(a);
sc.parallelize(1 to 1000, 1000).map { x => a; x }.groupBy { x => a; x }.count
```

Numbers on 3 r3.8xlarge instances on EC2
```
master branch: 5.648436068 s, 4.715361895 s, 5.360161877 s
with this change: 3.416348793 s, 1.477846558 s, 1.553432156 s
```

Author: Reynold Xin <rxin@apache.org>

Closes #1452 from rxin/broadcast-task and squashes the following commits:

762e0be [Reynold Xin] Warn large broadcasts.
ade6eac [Reynold Xin] Log broadcast size.
c3b6f11 [Reynold Xin] Added a unit test for clean up.
754085f [Reynold Xin] Explain why broadcasting serialized copy of the task.
04b17f0 [Reynold Xin] [SPARK-2521] Broadcast RDD object once per TaskSet (instead of sending it for every task).
put 'curRequestSize = 0' after 'logDebug' it

This is a minor change. We should first logDebug($curRequestSize) and then set it to 0.

Author: Lijie Xu <csxulijie@gmail.com>

Closes #1477 from JerryLead/patch-1 and squashes the following commits:

aed722d [Lijie Xu] put 'curRequestSize = 0' after 'logDebug' it
SPARK-2407: Added Parser of SQL SUBSTR()

follow-up of #1359

Author: chutium <teng.qiu@gmail.com>

Closes #1442 from chutium/master and squashes the following commits:

b49cc8a [chutium] SPARK-2407: Added Parser of SQL SUBSTRING() #1442
9a60ccf [chutium] SPARK-2407: Added Parser of SQL SUBSTR() #1442
06e933b [chutium] Merge https://github.com/apache/spark
c870172 [chutium] Merge https://github.com/apache/spark
094f773 [chutium] Merge https://github.com/apache/spark
88cb37d [chutium] Merge https://github.com/apache/spark
1de83a7 [chutium] SPARK-2407: Added Parse of SQL SUBSTR()
Revert "[SPARK-2521] Broadcast RDD object (instead of sending it along with every task)."

This reverts commit 7b8cd175254d42c8e82f0aa8eb4b7f3508d8fde2.
SPARK-2596 A tool for mirroring github pull requests on JIRA.

For a bunch of reasons we should automatically populate a JIRA with information about new pull requests when they arrive. I've written a small python script to do this that we can run from Jenkins every 5 or 10 minutes to keep things in sync.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #1496 from pwendell/github-integration and squashes the following commits:

55ad226 [Patrick Wendell] Small fix
afda547 [Patrick Wendell] Use sequence instead of dictiory for JIRA's
3e18cc1 [Patrick Wendell] Small edits
84c5606 [Patrick Wendell] SPARK-2596 A tool for mirroring github pull requests on JIRA.
SPARK-2596 HOTFIX: Deal with non-existent JIRAs.

A small bug that was found in our JIRA sync script.
Typo fix to the programming guide in the docs

Typo fix to the programming guide in the docs. Changed the word "distibuted" to "distributed".

Author: Cesar Arevalo <cesar@zephyrhealthinc.com>

Closes #1495 from cesararevalo/master and squashes the following commits:

0c2e3a7 [Cesar Arevalo] Typo fix to the programming guide in the docs
SPARK-2587: Fix error message in make-distribution.sh

make-distribution.sh gives a slightly off error message when using --with-hive.

Author: Mark Wagner <mwagner@mwagner-ld.linkedin.biz>

Closes #1489 from wagnermarkd/SPARK-2587 and squashes the following commits:

7b5d3ff [Mark Wagner] SPARK-2587: Fix error message in make-distribution.sh
[SPARK-2524] missing document about spark.deploy.retainedDrivers

https://issues.apache.org/jira/browse/SPARK-2524
The configuration on spark.deploy.retainedDrivers is undocumented but actually used
https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/deploy/master/Master.scala#L60

Author: lianhuiwang <lianhuiwang09@gmail.com>
Author: Wang Lianhui <lianhuiwang09@gmail.com>
Author: unknown <Administrator@taguswang-PC1.tencent.com>

Closes #1443 from lianhuiwang/SPARK-2524 and squashes the following commits:

64660fd [Wang Lianhui] address pwendell's comments
5f6bbb7 [Wang Lianhui] missing document about spark.deploy.retainedDrivers
44a3f50 [unknown] Merge remote-tracking branch 'upstream/master'
eacf933 [lianhuiwang] Merge remote-tracking branch 'upstream/master'
8bbfe76 [lianhuiwang] Merge remote-tracking branch 'upstream/master'
480ce94 [lianhuiwang] address aarondav comments
f2b5970 [lianhuiwang] bugfix worker DriverStateChanged state should match DriverState.FAILED
SPARK-2519 part 2. Remove pattern matching on Tuple2 in critical section...

...s of CoGroupedRDD and PairRDDFunctions

This also removes an unnecessary tuple creation in cogroup.

Author: Sandy Ryza <sandy@cloudera.com>

Closes #1447 from sryza/sandy-spark-2519-2 and squashes the following commits:

b6d9699 [Sandy Ryza] Remove missed Tuple2 match in CoGroupedRDD
a109828 [Sandy Ryza] Remove another pattern matching in MappedValuesRDD and revert some changes in PairRDDFunctions
be10f8a [Sandy Ryza] SPARK-2519 part 2. Remove pattern matching on Tuple2 in critical sections of CoGroupedRDD and PairRDDFunctions
[SPARK-2598] RangePartitioner's binary search does not use the given Ordering

We should fix this in branch-1.0 as well.

Author: Reynold Xin <rxin@apache.org>

Closes #1500 from rxin/rangePartitioner and squashes the following commits:

c0a94f5 [Reynold Xin] [SPARK-2598] RangePartitioner's binary search does not use the given Ordering.
[SPARK-2495][MLLIB] remove private[mllib] from linear models' constructors

This is part of SPARK-2495 to allow users construct linear models manually.

Author: Xiangrui Meng <meng@databricks.com>

Closes #1492 from mengxr/public-constructor and squashes the following commits:

a48b766 [Xiangrui Meng] remove private[mllib] from linear models' constructors
SPARK-2564. ShuffleReadMetrics.totalBlocksRead is redundant

Author: Sandy Ryza <sandy@cloudera.com>

Closes #1474 from sryza/sandy-spark-2564 and squashes the following commits:

35b8388 [Sandy Ryza] Fix compile error on upmerge
7b985fb [Sandy Ryza] Fix test compile error
43f79e6 [Sandy Ryza] SPARK-2564. ShuffleReadMetrics.totalBlocksRead is redundant
[SPARK-2552][MLLIB] stabilize logistic function in pyspark

to avoid overflow in `exp(x)` if `x` is large.

Author: Xiangrui Meng <meng@databricks.com>

Closes #1493 from mengxr/py-logistic and squashes the following commits:

259e863 [Xiangrui Meng] stabilize logistic function in pyspark
Improve scheduler delay tooltip.

As a result of shivaram's experience debugging long scheduler delay, I think we should improve the tooltip to point people in the right direction if scheduler delay is large.

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #1488 from kayousterhout/better_tooltips and squashes the following commits:

22176fd [Kay Ousterhout] Improve scheduler delay tooltip.
[SPARK-1945][MLLIB] Documentation Improvements for Spark 1.0

Standalone application examples are added to 'mllib-linear-methods.md' file written in Java.
This commit is related to the issue [Add full Java Examples in MLlib docs](https://issues.apache.org/jira/browse/SPARK-1945).
Also I changed the name of the sigmoid function from 'logit' to 'f'. This is because the logit function
is the inverse of sigmoid.

Thanks,
Michael

Author: Michael Giannakopoulos <miccagiann@gmail.com>

Closes #1311 from miccagiann/master and squashes the following commits:

8ffe5ab [Michael Giannakopoulos] Update code so as to comply with code standards.
f7ad5cc [Michael Giannakopoulos] Merge remote-tracking branch 'upstream/master'
38d92c7 [Michael Giannakopoulos] Adding PCA, SVD and LBFGS examples in Java. Performing minor updates in the already committed examples so as to eradicate the call of 'productElement' function whenever is possible.
cc0a089 [Michael Giannakopoulos] Modyfied Java examples so as to comply with coding standards.
b1141b2 [Michael Giannakopoulos] Added Java examples for Clustering and Collaborative Filtering [mllib-clustering.md & mllib-collaborative-filtering.md].
837f7a8 [Michael Giannakopoulos] Merge remote-tracking branch 'upstream/master'
15f0eb4 [Michael Giannakopoulos] Java examples included in 'mllib-linear-methods.md' file.