Added sample for reading from parquet files

Author: uc-msft

samples/features/sql-big-data-cluster/data-virtualization/README.md

@@ -10,7 +10,9 @@ In this example, you are going to create an external table in the SQL Server Mas
 
 1. Connect to SQL Server Master instance.
 
-1. Execute the [external-table-hdfs.sql](external-table-hdfs.sql).
+1. Execute the [external-table-hdfs-csv.sql](external-table-hdfs-csv.sql). This script demonstrates how to read CSV file(s) stored in HDFS.
+
+1. Before you use execute the *external-table-hdfs-parquet.sql* script, make sure you run the [../spark/spark-sql.ipynb](../spark/spark-sql.ipynb/) notebook to generate the sample parquet file. Execute the [external-table-hdfs-parquet.sql](external-table-hdfs-parquet.sql). This script demonstrates how to read parquet file(s) stored in HDFS. 
 
 ## Query data in Oracle from SQL Server master
 

…a-virtualization/external-table-hdfs.sql …rtualization/external-table-hdfs-csv.sqlsamples/features/sql-big-data-cluster/data-virtualization/external-table-hdfs.sql renamed to samples/features/sql-big-data-cluster/data-virtualization/external-table-hdfs-csv.sql samples/features/sql-big-data-cluster/data-virtualization/external-table-hdfs.sql renamed to samples/features/sql-big-data-cluster/data-virtualization/external-table-hdfs-csv.sql

@@ -18,7 +18,7 @@ WITH (
 -- is a special data source that is available in any new database in
 -- SQL Master instance.
 --
-CREATE EXTERNAL TABLE [web_clickstreams_hdfs]
+CREATE EXTERNAL TABLE [web_clickstreams_hdfs_csv]
 ("wcs_click_date_sk" BIGINT , "wcs_click_time_sk" BIGINT , "wcs_sales_sk" BIGINT , "wcs_item_sk" BIGINT , "wcs_web_page_sk" BIGINT , "wcs_user_sk" BIGINT)
 WITH
 (
@@ -42,11 +42,11 @@ SELECT
     SUM( CASE WHEN i_category_id = 7 THEN 1 ELSE 0 END) AS [Toys & Games],
     SUM( CASE WHEN i_category_id = 8 THEN 1 ELSE 0 END) AS [Movies & TV],
     SUM( CASE WHEN i_category_id = 9 THEN 1 ELSE 0 END) AS [Sports & Outdoors]
-  FROM [dbo].[web_clickstreams_hdfs]
+  FROM [dbo].[web_clickstreams_hdfs_csv]
   INNER JOIN item it ON (wcs_item_sk = i_item_sk
                         AND wcs_user_sk IS NOT NULL)
 GROUP BY  wcs_user_sk;
 GO
 
-DROP EXTERNAL TABLE [dbo].[web_clickstreams_hdfs];
+DROP EXTERNAL TABLE [dbo].[web_clickstreams_hdfs_csv];
 GO

samples/features/sql-big-data-cluster/data-virtualization/external-table-hdfs-parquet.sql

@@ -0,0 +1,47 @@
+USE sales
+GO
+
+-- Create file format for parquet file with appropriate properties.
+--
+CREATE EXTERNAL FILE FORMAT parquet_file
+WITH (
+    FORMAT_TYPE = PARQUET
+);
+
+-- Create external table over HDFS data source (SqlStoragePool) in
+-- SQL Server 2019 big data cluster. The SqlStoragePool data source
+-- is a special data source that is available in any new database in
+-- SQL Master instance.
+--
+CREATE EXTERNAL TABLE [web_clickstreams_hdfs_parquet]
+("wcs_click_date_sk" BIGINT , "wcs_click_time_sk" BIGINT , "wcs_sales_sk" BIGINT , "wcs_item_sk" BIGINT , "wcs_web_page_sk" BIGINT , "wcs_user_sk" BIGINT)
+WITH
+(
+    DATA_SOURCE = SqlStoragePool,
+	LOCATION = '/user/hive/warehouse/web_clickstreams',
+    FILE_FORMAT = parquet_file
+);
+GO
+
+-- Join external table with local tables
+-- 
+SELECT  
+    wcs_user_sk,
+    SUM( CASE WHEN i_category = 'Books' THEN 1 ELSE 0 END) AS book_category_clicks,
+    SUM( CASE WHEN i_category_id = 1 THEN 1 ELSE 0 END) AS [Home & Kitchen],
+    SUM( CASE WHEN i_category_id = 2 THEN 1 ELSE 0 END) AS [Music],
+    SUM( CASE WHEN i_category_id = 3 THEN 1 ELSE 0 END) AS [Books],
+    SUM( CASE WHEN i_category_id = 4 THEN 1 ELSE 0 END) AS [Clothing & Accessories],
+    SUM( CASE WHEN i_category_id = 5 THEN 1 ELSE 0 END) AS [Electronics],
+    SUM( CASE WHEN i_category_id = 6 THEN 1 ELSE 0 END) AS [Tools & Home Improvement],
+    SUM( CASE WHEN i_category_id = 7 THEN 1 ELSE 0 END) AS [Toys & Games],
+    SUM( CASE WHEN i_category_id = 8 THEN 1 ELSE 0 END) AS [Movies & TV],
+    SUM( CASE WHEN i_category_id = 9 THEN 1 ELSE 0 END) AS [Sports & Outdoors]
+  FROM [dbo].[web_clickstreams_hdfs_parquet]
+  INNER JOIN item it ON (wcs_item_sk = i_item_sk
+                        AND wcs_user_sk IS NOT NULL)
+GROUP BY  wcs_user_sk;
+GO
+
+DROP EXTERNAL TABLE [dbo].[web_clickstreams_hdfs_parquet];
+GO