Tiflash的使用介绍

1、创建一个products表

mysql> CREATE TABLE products (
    ->     id INT PRIMARY KEY AUTO_INCREMENT,
    ->     product_name VARCHAR(100),
    ->     price DECIMAL(13 , 2 )
    -> );
Query OK, 0 rows affected (0.17 sec)

2、查看products表结构

mysql> desc select count(*) from products;
+----------------------------+----------+-----------+----------------+---------------------------------+
| id                         | estRows  | task      | access object  | operator info                   |
+----------------------------+----------+-----------+----------------+---------------------------------+
| StreamAgg_16               | 1.00     | root      |                | funcs:count(Column#6)->Column#4 |
| └─TableReader_17           | 1.00     | root      |                | data:StreamAgg_8                |
|   └─StreamAgg_8            | 1.00     | cop[tikv] |                | funcs:count(1)->Column#6        |
|     └─TableFullScan_15     | 10000.00 | cop[tikv] | table:products | keep order:false, stats:pseudo  |
+----------------------------+----------+-----------+----------------+---------------------------------+
4 rows in set (0.00 sec)

注意此时是cop[tikv]，证明还不是tiflash的数据结构

3、为tidb的表products创建tiflash副本

mysql> ALTER TABLE products SET TIFLASH REPLICA 1;
Query OK, 0 rows affected (0.19 sec)

4、再次查看products表结构

mysql> desc select count(*) from products;
+------------------------------+----------+--------------+----------------+---------------------------------+
| id                           | estRows  | task         | access object  | operator info                   |
+------------------------------+----------+--------------+----------------+---------------------------------+
| HashAgg_21                   | 1.00     | root         |                | funcs:count(Column#6)->Column#4 |
| └─TableReader_23             | 1.00     | root         |                | data:ExchangeSender_22          |
|   └─ExchangeSender_22        | 1.00     | mpp[tiflash] |                | ExchangeType: PassThrough       |
|     └─HashAgg_9              | 1.00     | mpp[tiflash] |                | funcs:count(1)->Column#6        |
|       └─TableFullScan_20     | 10000.00 | mpp[tiflash] | table:products | keep order:false, stats:pseudo  |
+------------------------------+----------+--------------+----------------+---------------------------------+
5 rows in set (0.00 sec)

此时为mpp[tiflash]，表示已经创建了tiflash的副本

如上，我们可以看到当tidb的环境tikv与tiflash部署成功之后，想使用tiflash的引擎，按照如上的操作即可完成