connect to ShardingSphere‐Proxy, if ShardingSphere‐Proxy does not create a database or does not add a resource, the client connection will fail? . . . . . . . . . . . . . . . . . . . . . . . . . . . 457 8 adding a data source using DistSQL? . . . . . . . . . . . . . . . . . 459 8.5.2 DistSQL How to solve Resource [xxx] is still used by [Sin- gleTableRule]. exception when dropping a data source using DistSQL be saved persistently. In single data node, transactions are only restricted to the access and control of single database re‐ sources, called local transactions. Almost all the mature relational databases

connect to ShardingSphere‐Proxy, if ShardingSphere‐Proxy does not create a database or does not add a resource, the client connection will fail? . . . . . . . . . . . . . . . . . . . . . . . . . . . 496 8 adding a data source using DistSQL? . . . . . . . . . . . . . . . . . 498 8.5.2 DistSQL How to solve Resource [xxx] is still used by [Sin- gleTableRule]. exception when dropping a data source using DistSQL be saved persistently. In single data node, transactions are only restricted to the access and control of single database re‐ sources, called local transactions. Almost all the mature relational databases

connect to ShardingSphere‐Proxy, if ShardingSphere‐Proxy does not create a Schema or does not add a Resource, the client connection will fail? . . . . . . . . . . . . . . . . . . . . . . . . . . . 347 7 adding a data source using DistSQL? . . . . . . . . . . . . . . . 350 7.8.19 [DistSQL] How to solve Resource [xxx] is still used by [Sin- gleTableRule]. exception when dropping a data source using DistSQL DistSQL is divided into RDL, RQL and RAL. • RDL (Resource & Rule Definition Language) responsible for the definition of resources and rules; • RQL (Resource & Rule Query Language) responsible for the query

connect to ShardingSphere‐Proxy, if ShardingSphere‐Proxy does not create a Schema or does not add a Resource, the client connection will fail? . . . . . . . . . . . . . . . . . . . . . . . . . . . 359 7 adding a data source using DistSQL? . . . . . . . . . . . . . . . 362 7.8.19 [DistSQL] How to solve Resource [xxx] is still used by [Sin- gleTableRule]. exception when dropping a data source using DistSQL DistSQL is divided into RDL, RQL and RAL. • RDL (Resource & Rule Definition Language) responsible for the definition of resources and rules; • RQL (Resource & Rule Query Language) responsible for the query

DistSQL is divided into RDL, RQL and RAL. • RDL (Resource & Rule Definition Language) responsible for the definition of resources and rules; • RQL (Resource & Rule Query Language) responsible for the query query of resources and rules; • RAL (Resource & Rule Administration Language) responsible for the added‐on administrator fea‐ ture of hint, transaction type switch, sharding execute planning and so on TABLE t_order CHECK TABLE t_order SET RESOURCE GROUP group_name DROP RESOURCE GROUP group_name CREATE RESOURCE GROUP group_name TYPE = SYSTEM ALTER RESOURCE GROUP rg1 VCPU = 0‐63 4.1. DB Compatibility

be saved persistently. In single data node, transactions are only restricted to the access and control of single database re‐ sources, called local transactions. Almost all the mature relational databases transaction adopts the concepts including AP(application program), TM(transaction manager) and RM(resource manager) to ensure the strong consistency of distributed transactions. Those concepts are abstracted during the exe‐ cution of transactions. Flexible transaction is to move mutex operations from the resource level to the 8.2. Distributed Transaction 35 Apache ShardingSphere document business level through

be saved persistently. In single data node, transactions are only restricted to the access and control of single database re‐ sources, called local transactions. Almost all the mature relational databases transaction adopts the concepts including AP(application program), TM(transaction manager) and RM(resource manager) to ensure the strong consistency of distributed transactions. Those concepts are abstracted during the exe‐ cution of transactions. Flexible transaction is to move mutex operations from the resource level to the 8.2. Distributed Transaction 35 Apache ShardingSphere document business level through

95 v Apache ShardingSphere ElasticJob document Through the functions of flexible scheduling, resource management and job management, it creates a distributed scheduling solution suitable for Internet improvement – Job processing capacity is flexible and scalable with the allocation of resources • Resource Assign – Execute job on suitable time and assigned resources – Aggregation same job to same job sharding item sequence number stores detailed information. The child node under each shard is used to control and record the running status of the shard. Node details description： 5.2. Elastic Schedule 11

operations, including the SET database manage‐ ment order used to set the database and transaction control statement as TCL. In this case, all physical databases matched with the name are traversed according engine is to automat‐ ically balance between the resource control and the execution efficiency. Connection Mode From the perspective of resource control, the connection number of the business side’s visit should be limited. It can effectively prevent some certain business from occupying exces‐ sive resource, exhausting database connection resources and influencing the normal use of other busi‐ nesses

RDL、RQL 和 SCTL 这三种具体类型。 • RDL（Resource & Rule Definition Language）负责资源和规则的创建、修改和删除； • RQL（Resource & Rule Query Language）负责资源和规则的查询和展现； • SCTL（ShardingSphere Control Language）负责 Hint、事务类型切换、分片执行计划查询等增量 RDL 的使用。 数据源资源 定义 ADD RESOURCE dataSource [, dataSource] ... dataSource: dataSourceName(HOST=hostName,PORT=port,DB=dbName,USER=user [, PASSWORD=password]) DROP RESOURCE dataSourceName [, dataSourceName] dataSourceName 不允许被添加 • DROP RESOURCE 只会删除逻辑资源，不会删除真实的数据源 • 被规则引用的资源将无法被删除 示例 ADD RESOURCE resource_0 ( HOST=127.0.0.1, PORT=3306, DB=db0, USER=root, PASSWORD=root ),resource_1 ( HOST=127.0.0.1, PORT=3306