使用手册

使用手册

环境要求

纯 JAVA 开发，JDK 建议 1.8 以上版本。

支持迁移场景如下：

源端 目标端
MySQL(5.1.15 ~ 5.7.x) MySQL
PostgreSQL(9.4 ~ ) PostgreSQL
openGauss(2.1.0) openGauss

注意：

如果后端连接 MySQL 数据库，请下载 mysql-connector-java-5.1.47.jar，并将其放入 ${shardingsphere-proxy}/lib 目录。

权限要求

MySQL 需要开启 binlog，且迁移时所使用用户需要赋予 Replication 相关权限。

+-----------------------------------------+---------------------------------------+
| Variable_name                           | Value                                 |
+-----------------------------------------+---------------------------------------+
| log_bin                                 | ON                                    |
| binlog_format                           | ROW                                   |
| binlog_row_image                        | FULL                                  |
+-----------------------------------------+---------------------------------------+

+------------------------------------------------------------------------------+
|Grants for ${username}@${host}                                                |
+------------------------------------------------------------------------------+
|GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO ${username}@${host}     |
|.......                                                                       |
+------------------------------------------------------------------------------+

PostgreSQL 需要开启 test_decoding

DistSQL 接口

弹性迁移组件提供了 DistSQL 接口

预览当前分片规则

示例：

preview select count(1) from t_order;

返回信息：

mysql> preview select count(1) from t_order;
+------------------+--------------------------------+
| data_source_name | sql                            |
+------------------+--------------------------------+
| ds_0             | select count(1) from t_order_0 |
| ds_0             | select count(1) from t_order_1 |
| ds_1             | select count(1) from t_order_0 |
| ds_1             | select count(1) from t_order_1 |
+------------------+--------------------------------+
4 rows in set (0.00 sec)

创建迁移任务

  1. 添加新的数据源

详情请参见RDL#数据源资源。

示例：

ADD RESOURCE ds_2 (
    URL="jdbc:mysql://127.0.0.1:3306/db2?serverTimezone=UTC&useSSL=false",
    USER=root,
    PASSWORD=root,
    PROPERTIES("maximumPoolSize"=10,"idleTimeout"="30000")
);
-- ds_3, ds_4
  1. 修改分片规则

详情请参见RDL#数据分片。

示例：

ALTER SHARDING TABLE RULE t_order (
RESOURCES(ds_2, ds_3, ds_4),
SHARDING_COLUMN=order_id,
TYPE(NAME=hash_mod,PROPERTIES("sharding-count"=10)),
GENERATED_KEY(COLUMN=another_id,TYPE(NAME=snowflake,PROPERTIES("worker-id"=123)))
);

比如说RESOURCES和sharding-count修改了会触发迁移。

查询所有迁移任务

详情请参见RAL#弹性伸缩。

示例：

show scaling list;

返回信息：

mysql> show scaling list;
+--------------------+-----------------------+----------------------+--------+---------------------+---------------------+
| id                 | tables                | sharding_total_count | active | create_time         | stop_time           |
+--------------------+-----------------------+----------------------+--------+---------------------+---------------------+
| 659853312085983232 | t_order_item, t_order | 2                    | 0      | 2021-10-26 20:21:31 | 2021-10-26 20:24:01 |
| 660152090995195904 | t_order_item, t_order | 2                    | 0      | 2021-10-27 16:08:43 | 2021-10-27 16:11:00 |
+--------------------+-----------------------+----------------------+--------+---------------------+---------------------+
2 rows in set (0.04 sec)

查询迁移任务进度

示例：

show scaling status {jobId};

返回信息：

mysql> show scaling status 660152090995195904;
+------+-------------+----------+-------------------------------+--------------------------+
| item | data_source | status   | inventory_finished_percentage | incremental_idle_minutes |
+------+-------------+----------+-------------------------------+--------------------------+
| 0    | ds_1        | FINISHED | 100                           | 2834                     |
| 1    | ds_0        | FINISHED | 100                           | 2834                     |
+------+-------------+----------+-------------------------------+--------------------------+
2 rows in set (0.00 sec)

当前迁移任务已完成，新的分片规则已生效。如果迁移失败，新的分片规则不会生效。

status的取值：

取值 描述
PREPARING 准备中
RUNNING 运行中
EXECUTE_INVENTORY_TASK 全量迁移中
EXECUTE_INCREMENTAL_TASK 增量迁移中
ALMOST_FINISHED 基本完成
FINISHED 已完成
PREPARING_FAILURE 准备阶段失败
EXECUTE_INVENTORY_TASK_FAILURE 全量迁移阶段失败
EXECUTE_INCREMENTAL_TASK_FAILURE 增量迁移阶段失败

预览新的分片规则是否生效

示例：

preview select count(1) from t_order;

返回信息：

mysql> preview select count(1) from t_order;
+------------------+--------------------------------+
| data_source_name | sql                            |
+------------------+--------------------------------+
| ds_2             | select count(1) from t_order_0 |
| ds_2             | select count(1) from t_order_1 |
| ds_3             | select count(1) from t_order_0 |
| ds_3             | select count(1) from t_order_1 |
| ds_4             | select count(1) from t_order_0 |
| ds_4             | select count(1) from t_order_1 |
+------------------+--------------------------------+
6 rows in set (0.01 sec)

其他DistSQL

详情请参见RAL#弹性伸缩。