data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds t_order ORDER BY id LIMIT 1000000, 10 This SQL will make MySQL acquire another 10 records after skipping 1,000,000 records when it is not able to use indexes. Its performance can thus be deduced. In sharding and rolling back in other machines after the service is down. • Savepoint. • In the transaction block, the SQL execution is abnormal, and run Commit, and data remains con‐ sistent. XA Transaction managed

data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds committing and rolling back in other machines after the service is down. • MySQL, in the transaction block, the SQL execution is abnormal, and run Commit, and data re‐ mains consistent. • After XA transactions compute node in a ShardingSphere cluster exceeds its load, the circuit breaker function is used to block the traffic to the compute node, to ensure that the whole cluster continues to provide stable services

data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds t_order ORDER BY id LIMIT 1000000, 10 This SQL will make MySQL acquire another 10 records after skipping 1,000,000 records when it is not able to use indexes. Its performance can thus be deduced. In sharding database can commit. XA Supported • Support Savepoint; • PostgreSQL/OpenGauss, in the transaction block, the SQL execution is abnormal，then run Com- mit，transactions are automatically rollback; • Support

data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds committing and rolling back in other machines after the service is down. • MySQL, in the transaction block, the SQL execution is abnormal, and run Commit, and data re‐ mains consistent. • After XA transactions compute node in a ShardingSphere cluster exceeds its load, the circuit breaker function is used to block the traffic to the compute node, to ensure that the whole cluster continues to provide stable services

data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds so this command is executed once on any physical table. Ignore Route Ignore route is used to block the operation of SQL to the database. For example: USE order_db; This command will not be executed t_order ORDER BY id LIMIT 1000000, 10 This SQL will make MySQL acquire another 10 records after skipping 1,000,000 records when it is not able to use indexes. Its performance can thus be deduced. In sharding

data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds t_order ORDER BY id LIMIT 1000000, 10 This SQL will make MySQL acquire another 10 records after skipping 1,000,000 records when it is not able to use indexes. Its performance can thus be deduced. In sharding so this command is executed once on any physical table. Ignore Route Ignore route is used to block the operation of SQL to the database. For example: USE order_db; This command will not be executed

data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds commit. XA Transaction Supported • Support Savepoint; • PostgreSQL/OpenGauss, in the transaction block, the SQL execution is abnormal，then run Com- mit，transactions are automatically rollback; • Support committing and rolling back in other machines after the service is down; • MySQL,in the transaction block, the SQL execution is abnormal, and run Commit, and data re‐ mains consistent. BASE Transaction

data in native distributed NoSQL. But its incom‐ patibility with SQL and imperfection in ecosystem block it from defeating the relational database in the competition, so the relational database still holds commit. XA Transaction Supported • Support Savepoint; • PostgreSQL/OpenGauss, in the transaction block, the SQL execution is abnormal，then run Com- mit，transactions are automatically rollback; • Support committing and rolling back in other machines after the service is down; • MySQL,in the transaction block, the SQL execution is abnormal, and run Commit, and data re‐ mains consistent. BASE Transaction

Auto-generated catch block e.printStackTrace(); } } if(preparedStatement!=null){ try { preparedStatement.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); if(connection!=null){ try { connection.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } 上边使用 jdbc 的原始方法（未经封装）实现了查询数据库表记录的操作。 1.1.2 jdbc 编程步骤： 1、 加载数据库驱动

"batchSize":1000,"shardingSize":10000000} | {"workerThread ":20,"batchSize":1000} | {"type":"MEMORY","props":{"block-queue-size":"2000"}} | +--------------------------------------------------------------+------------------- (TYPE(NAME='TPS', PROPERTIES('tps'='2000')))), STREAM_CHANNEL ( TYPE(NAME='MEMORY',PROPERTIES('block-queue-size'='2000'))) ); 保留字 ALTER、MIGRATION、RULE、READ、WRITE、WORKER_THREAD、BATCH_SIZE、SHARDING_SIZE、 "batchSize":1000,"shardingSize":10000000} | {"workerThread ":20,"batchSize":1000} | {"type":"MEMORY","props":{"block-queue-size":"2000"}} | 9.2. ShardingSphere-Proxy 373 Apache ShardingSphere document +---------