我们正在努力将现有应用程序移植到 Azure SQL 数据仓库。为了更好地了解 Azure SQL 数据仓库的性能/工作负载管理特性/功能，我设置了一个我认为非常简单的测试。
我加载了一个静态表，我们的业务日历，包含大约 20k 行（即对于并行数据仓库来说非常小）。然后，我使用如下模式生成了该单个表的所有可能查询：
SELECT current_timestamp,COUNT(1) FROM
( SELECT C1, ..., Cn , COUNT(1) AS _A_ROW_COUNT
FROM schema.view_to_table GROUP BY C1, ..., Cn) DER
吉文斯：
- DWU 设置为 1000。
- 启动了 35 个并发线程。
- 在 small_rc 中运行的所有线程。（即，每个查询使用 1 个插槽。）
- 使用带有初始连接的 sqlcmd，然后在每次 SELECT 后提交
- 在通过 Express 路由连接的非 Azure VM 上运行。选择外部 SELECT COUNT() 构造以确保网络流量最小。
- 堆表的使用提供了比默认列存储更好的结果（如预期的那样）。（需要使用聚集索引进行测试。）
- 表按主键列分布。
背景/偏见 - 我曾与许多其他 MPP 数据库合作过。
结果
- 查询在 10-20 秒内运行，这比我对这种简单工作的预期要长得多。
- 当我提交每个线程时，我在每个新线程之间睡觉。初始查询运行得更快，随着线程数增加到 35，平均运行时间急剧下降。
我如何理解存在什么瓶颈？
当然，我会在其他 DWU 设置下重新运行测试，看看它是否会影响专门的 small_rc 工作负载。
附录 - 示例查询计划
<?xml version="1.0" encoding="utf-8"?>
<dsql_query number_nodes="10" number_distributions="60" number_distributions_per_node="6">
<sql>SELECT current_timestamp,COUNT(1) FROM ( SELECT GREGORIAN_DATE, WM_MONTH, MON_MULT, FRI_MULT , COUNT(1) AS _A_ROW_COUNT FROM AR_WM_VM.CALENDAR_DAY GROUP BY GREGORIAN_DATE, WM_MONTH, MON_MULT, FRI_MULT) DER</sql>
<dsql_operations total_cost="0.260568" total_number_operations="8">
<dsql_operation operation_type="RND_ID">
<identifier>TEMP_ID_21523</identifier>
</dsql_operation>
<dsql_operation operation_type="ON">
<location permanent="false" distribution="AllDistributions" />
<sql_operations>
<sql_operation type="statement">CREATE TABLE [tempdb].[dbo].[TEMP_ID_21523] ([col] DATE ) WITH(DATA_COMPRESSION=PAGE);</sql_operation>
</sql_operations>
</dsql_operation>
<dsql_operation operation_type="SHUFFLE_MOVE">
<operation_cost cost="0.258648" accumulative_cost="0.258648" average_rowsize="3" output_rows="2155.4" GroupNumber="76" />
<source_statement>SELECT [T1_1].[col] AS [col]
FROM (SELECT dateadd(dd, CAST ((364) AS INT), [T2_1].[calendar_date]) AS [col]
FROM [db_ARdev1].[AR_CORE_DIM_TABLES].[calendar_dim] AS T2_1) AS T1_1</source_statement>
<destination_table>[TEMP_ID_21523]</destination_table>
<shuffle_columns>col;</shuffle_columns>
</dsql_operation>
<dsql_operation operation_type="ON">
<location permanent="false" distribution="Control" />
<sql_operations>
<sql_operation type="statement">CREATE TABLE [tempdb].[QTables].[QTable_3ff26b5253004eec9d9ca50492bab1e2] ([col] BIGINT ) WITH(DATA_COMPRESSION=PAGE);</sql_operation>
</sql_operations>
</dsql_operation>
<dsql_operation operation_type="PARTITION_MOVE">
<operation_cost cost="0.00192" accumulative_cost="0.260568" average_rowsize="8" output_rows="1" GroupNumber="93" />
<location distribution="AllDistributions" />
<source_statement>SELECT [T1_1].[col] AS [col]
FROM (SELECT COUNT_BIG(CAST ((1) AS INT)) AS [col]
FROM (SELECT 0 AS [col]
FROM [tempdb].[dbo].[TEMP_ID_21523] AS T3_1
INNER JOIN
(SELECT CASE
WHEN ([T4_1].[wm_week_day_nbr] = CAST ((3) AS SMALLINT)) THEN CAST ((1) AS INT)
ELSE CAST ((0) AS INT)
END AS [col],
CASE
WHEN ([T4_1].[wm_week_day_nbr] = CAST ((7) AS SMALLINT)) THEN CAST ((1) AS INT)
ELSE CAST ((0) AS INT)
END AS [col1],
[T4_1].[calendar_date] AS [calendar_date],
[T4_1].[fiscal_month_nbr] AS [fiscal_month_nbr]
FROM [db_ARdev1].[AR_CORE_DIM_TABLES].[calendar_dim] AS T4_1) AS T3_2
ON ([T3_2].[calendar_date] = [T3_1].[col])
GROUP BY [T3_2].[calendar_date], [T3_2].[fiscal_month_nbr], [T3_2].[col], [T3_2].[col1]) AS T2_1
GROUP BY [T2_1].[col]) AS T1_1</source_statement>
<destination>Control</destination>
<destination_table>[QTable_3ff26b5253004eec9d9ca50492bab1e2]</destination_table>
</dsql_operation>
<dsql_operation operation_type="ON">
<location permanent="false" distribution="AllDistributions" />
<sql_operations>
<sql_operation type="statement">DROP TABLE [tempdb].[dbo].[TEMP_ID_21523]</sql_operation>
</sql_operations>
</dsql_operation>
<dsql_operation operation_type="RETURN">
<location distribution="Control" />
<select>SELECT [T1_1].[col1] AS [col],
[T1_1].[col] AS [col1]
FROM (SELECT CONVERT (INT, [T2_1].[col], 0) AS [col],
isnull(CONVERT (DATETIME, N'2016-10-03 13:04:34.203', 0), CONVERT (DATETIME, N'2016-10-03 13:04:34.203', 0)) AS [col1]
FROM (SELECT ISNULL([T3_1].[col], CONVERT (BIGINT, 0, 0)) AS [col]
FROM (SELECT SUM([T4_1].[col]) AS [col]
FROM [tempdb].[QTables].[QTable_3ff26b5253004eec9d9ca50492bab1e2] AS T4_1) AS T3_1) AS T2_1) AS T1_1</select>
</dsql_operation>
<dsql_operation operation_type="ON">
<location permanent="false" distribution="Control" />
<sql_operations>
<sql_operation type="statement">DROP TABLE [tempdb].[QTables].[QTable_3ff26b5253004eec9d9ca50492bab1e2]</sql_operation>
</sql_operations>
</dsql_operation>
</dsql_operations>
</dsql_query>