Add configuration value: compute.default_index_type (#723)

related with #722  i added compute.default_index_type

databricks/koalas/config.py

@@ -34,6 +34,9 @@
     # For example, this value determines whether the repr() for a dataframe prints out fully or
     # just a truncated repr.
     "display.max_rows": 1000,  # TODO: None should support unlimited.
+
+    # This sets the default index type: sequence, distributed and distributed-sequence.
+    "compute.default_index_type": "sequence",
 }  # type: Dict[str, Any]
 
 

databricks/koalas/internal.py

@@ -19,7 +19,6 @@
 """
 
 from typing import Dict, List, Optional, Tuple, Union
-import os
 from itertools import accumulate
 
 import numpy as np
@@ -32,6 +31,7 @@
 from pyspark.sql.types import DataType, StructField, StructType, to_arrow_type, LongType
 
 from databricks import koalas as ks  # For running doctests and reference resolution in PyCharm.
+from databricks.koalas.config import get_option
 from databricks.koalas.typedef import infer_pd_series_spark_type
 from databricks.koalas.utils import column_index_level, default_session, lazy_property, scol_for
 
@@ -417,8 +417,7 @@ def attach_default_index(sdf):
         This method attaches a default index to Spark DataFrame. Spark does not have the index
         notion so corresponding column should be generated.
 
-        There are three types of default index that can be controlled by `DEFAULT_INDEX`
-        environment variable.
+        There are three types of default index can be configured by `compute.default_index_type`
 
         - sequence: It implements a sequence that increases one by one, by Window function without
             specifying partition. Therefore, it ends up with whole partition in single node.
@@ -474,7 +473,7 @@ def attach_default_index(sdf):
             [25769803776, 60129542144, 94489280512]
 
         """
-        default_index_type = os.environ.get("DEFAULT_INDEX", "sequence")
+        default_index_type = get_option("compute.default_index_type")
         if default_index_type == "sequence":
             sequential_index = F.row_number().over(
                 Window.orderBy(F.monotonically_increasing_id().asc())) - 1
@@ -521,7 +520,7 @@ def default_index(pdf):
             return sdf.select(
                 F.monotonically_increasing_id().alias("__index_level_0__"), *scols)
         else:
-            raise ValueError("'DEFAULT_INDEX' environment variable should be one of 'sequence',"
+            raise ValueError("'compute.default_index_type' should be one of 'sequence',"
                              " 'distributed-sequence' and 'distributed'")
 
     @lazy_property

databricks/koalas/tests/test_default_index.py

@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-import os
-
 import pandas as pd
 
 from databricks import koalas as ks
+from databricks.koalas.config import set_option, reset_option
 from databricks.koalas.testing.utils import ReusedSQLTestCase, TestUtils
 
 
@@ -26,13 +25,12 @@ class OneByOneDefaultIndexTest(ReusedSQLTestCase, TestUtils):
     @classmethod
     def setUpClass(cls):
         super(OneByOneDefaultIndexTest, cls).setUpClass()
-        cls.default_index = os.environ.get('DEFAULT_INDEX', 'sequence')
-        os.environ['DEFAULT_INDEX'] = 'sequence'
+        set_option('compute.default_index_type', 'sequence')
 
     @classmethod
     def tearDownClass(cls):
         super(OneByOneDefaultIndexTest, cls).tearDownClass()
-        os.environ['DEFAULT_INDEX'] = cls.default_index
+        reset_option('compute.default_index_type')
 
     def test_default_index(self):
         sdf = self.spark.range(1000)
@@ -44,13 +42,12 @@ class DistributedOneByOneDefaultIndexTest(ReusedSQLTestCase, TestUtils):
     @classmethod
     def setUpClass(cls):
         super(DistributedOneByOneDefaultIndexTest, cls).setUpClass()
-        cls.default_index = os.environ.get('DEFAULT_INDEX', 'sequence')
-        os.environ['DEFAULT_INDEX'] = 'distributed-sequence'
+        set_option('compute.default_index_type', 'distributed-sequence')
 
     @classmethod
     def tearDownClass(cls):
         super(DistributedOneByOneDefaultIndexTest, cls).tearDownClass()
-        os.environ['DEFAULT_INDEX'] = cls.default_index
+        reset_option('compute.default_index_type')
 
     def test_default_index(self):
         sdf = self.spark.range(1000)
@@ -62,13 +59,12 @@ class DistributedDefaultIndexTest(ReusedSQLTestCase, TestUtils):
     @classmethod
     def setUpClass(cls):
         super(DistributedDefaultIndexTest, cls).setUpClass()
-        cls.default_index = os.environ.get('DEFAULT_INDEX', 'sequence')
-        os.environ['DEFAULT_INDEX'] = 'distributed'
+        set_option('compute.default_index_type', 'distributed')
 
     @classmethod
     def tearDownClass(cls):
         super(DistributedDefaultIndexTest, cls).tearDownClass()
-        os.environ['DEFAULT_INDEX'] = cls.default_index
+        reset_option('compute.default_index_type')
 
     def test_default_index(self):
         sdf = self.spark.range(1000)