# 步骤3：调优表操作具体步骤
#### 选择存储方式
此实践中所使用的样例表为典型的TPC-DS表，是典型的多字段表，统计分析类查询场景多，因此选择列存存储方式。
```
WITH (ORIENTATION = column)
```
#### 选择压缩级别
在[步骤1：创建初始表并加载样例数据](https://support.huaweicloud.com/bestpractice-dws/dws_05_0009.html)中没有指定压缩比，DWS默认为用户选择LOW级别压缩比。在这一步中把压缩比调整为MIDDLE级别，进行验证对比。
增加存储方式和压缩比后的建表样例如下：
```
CREATE TABLE store_sales
(
    ss_sold_date_sk           integer                       ,
    ss_sold_time_sk           integer                       ,
    ss_item_sk                integer               not null,
    ss_customer_sk            integer                       ,
    ss_cdemo_sk               integer                       ,
    ss_hdemo_sk               integer                       ,
    ss_addr_sk                integer                       ,
    ss_store_sk               integer                       ,
    ss_promo_sk               integer                       ,
    ss_ticket_number          bigint               not null,
    ss_quantity               integer                       ,
    ss_wholesale_cost         decimal(7,2)                  ,
    ss_list_price             decimal(7,2)                  ,
    ss_sales_price            decimal(7,2)                  ,
    ss_ext_discount_amt       decimal(7,2)                  ,
    ss_ext_sales_price        decimal(7,2)                  ,
    ss_ext_wholesale_cost     decimal(7,2)                  ,
    ss_ext_list_price         decimal(7,2)                  ,
    ss_ext_tax                decimal(7,2)                  ,
    ss_coupon_amt             decimal(7,2)                  ,
    ss_net_paid               decimal(7,2)                  ,
    ss_net_paid_inc_tax       decimal(7,2)                  ,
    ss_net_profit             decimal(7,2)                  
) 
WITH (ORIENTATION = column,COMPRESSION=middle);
```
#### 选择分布方式
依据[步骤2：测试初始表结构下的系统性能并建立基线](https://support.huaweicloud.com/bestpractice-dws/dws_05_0010.html)中基线的各表大小，分布方式设置如下：
| 表名                     | 行数        | 分布方式        |
|:---|:---|:---|
| Store_Sales            | 287997024 | Hash        |
| Date_Dim               | 73049     | Replication |
| Store                  | 402       | Replication |
| Item                   | 204000    | Replication |
| Time_Dim               | 86400     | Replication |
| Promotion              | 1000      | Replication |
| Customer_Demographics  | 1920800   | Hash        |
| Customer_Address       | 1000000   | Hash        |
| Household_Demographics | 7200      | Replication |
| Customer               | 1981703   | Hash        |
| Income_Band            | 20        | Replication |
   
#### 选择分布列
当表的分布方式选择了Hash分布策略时，分布列选取至关重要。在这一步中，建议按照[选择分布列](https://support.huaweicloud.com/bestpractice-dws/dws_05_0076.html#ZH-CN_TOPIC_0000001235882342__section776165384613)选择分布键：
选择各表的主键作为Hash表分布键。
| 表名                     | 记录数       | 分布方式        | 分布键           |
|:---|:---|:---|:---|
| Store_Sales            | 287997024 | Hash        | ss_item_sk    |
| Date_Dim               | 73049     | Replication | -             |
| Store                  | 402       | Replication | -             |
| Item                   | 204000    | Replication | -             |
| Time_Dim               | 86400     | Replication | -             |
| Promotion              | 1000      | Replication | -             |
| Customer_Demographics  | 1920800   | Hash        | cd_demo_sk    |
| Customer_Address       | 1000000   | Hash        | ca_address_sk |
| Household_Demographics | 7200      | Replication | -             |
| Customer               | 1981703   | Hash        | c_customer_sk |
| Income_Band            | 20        | Replication | -             |