[SPARK-15933][SQL][STREAMING] Refactored DF reader-writer to use readStream and writeStream for streaming DFs

## What changes were proposed in this pull request?
Currently, the DataFrameReader/Writer has method that are needed for streaming and non-streaming DFs. This is quite awkward because each method in them through runtime exception for one case or the other. So rather having half the methods throw runtime exceptions, its just better to have a different reader/writer API for streams.

- [x] Python API!!

## How was this patch tested?
Existing unit tests + two sets of unit tests for DataFrameReader/Writer and DataStreamReader/Writer.

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

Closes #13653 from tdas/SPARK-15933.

1 files changed, 4 insertions, 4 deletions

diff --git a/python/pyspark/sql/streaming.py b/python/pyspark/sql/streaming.py
index bb4e62cdd6..0edaa51549 100644
--- a/python/pyspark/sql/streaming.py
+++ b/python/pyspark/sql/streaming.py
@@ -119,7 +119,7 @@ class ContinuousQueryManager(object):
     def active(self):
         """Returns a list of active queries associated with this SQLContext
 
-        >>> cq = df.write.format('memory').queryName('this_query').startStream()
+        >>> cq = df.writeStream.format('memory').queryName('this_query').start()
         >>> cqm = spark.streams
         >>> # get the list of active continuous queries
         >>> [q.name for q in cqm.active]
@@ -134,7 +134,7 @@ class ContinuousQueryManager(object):
         """Returns an active query from this SQLContext or throws exception if an active query
         with this name doesn't exist.
 
-        >>> cq = df.write.format('memory').queryName('this_query').startStream()
+        >>> cq = df.writeStream.format('memory').queryName('this_query').start()
         >>> cq.name
         u'this_query'
         >>> cq = spark.streams.get(cq.id)
@@ -236,7 +236,7 @@ def _test():
 
     globs = pyspark.sql.streaming.__dict__.copy()
     try:
-        spark = SparkSession.builder.enableHiveSupport().getOrCreate()
+        spark = SparkSession.builder.getOrCreate()
     except py4j.protocol.Py4JError:
         spark = SparkSession(sc)
 
@@ -245,7 +245,7 @@ def _test():
     globs['spark'] = spark
     globs['sqlContext'] = SQLContext.getOrCreate(spark.sparkContext)
     globs['df'] = \
-        globs['spark'].read.format('text').stream('python/test_support/sql/streaming')
+        globs['spark'].readStream.format('text').load('python/test_support/sql/streaming')
 
     (failure_count, test_count) = doctest.testmod(
         pyspark.sql.streaming, globs=globs,