## A Relaxed Guide to memory_order_relaxed Hans Boehm Paul E. McKenney Google Facebook CPPCON 2020 ## std::atomic/std::atomic_ref and memory_order_relaxed - C++ atomic operations are sequentially consistent simple threads-as-interleaving semantics - by passing memory order enum values to explicit atomic operations. - In particular, memory_order_relaxed allows arbitrary visibility reordering with respect to to accesses to other locations. ## What is Not to Like About memory order relaxed? - Just a load, just a store: Full control, excellent efficiency and scalability! ☐ Assuming aligned machine-sized atomic

<id_of_pet_to_delete>;ORDER BY clauseSELECT <column_name> FROM <table_name> ORDER BY <column_name> <ASC|DESC>;Sort the either ascending (ASC) or descending (DESC) order based on the column(s) listed.SELECT * FROM pets ORDER BY name ASC; SELECT weight FROM pets ORDER BY name DESC; ##

524 /metadata/\${databaseName}/rules/sharding/tables/t_order/versions/0 525 /metadata/databaseName/schemas/\{schemaName\}/tables/t_order/versions/0 525 /nodes/compute_nodes 526 /nodes/qualified_data_sources Automatic Execution Engine ..... 546 12.4.11 Merger Engine ..... 550 Traversal Merger ..... 550 Order-by Merger ..... 550 Group-by Merger ..... 552 Aggregation Merger ..... 555 Pagination Merger ... 583 13.6.4 Other Why does Oracle database throw "Order by value must implement Comparable" exception when using Timestamp Order By? ..... 583 13.6.5 Other In Windows environment, when cloning

Connection Mode 251 Automatic Execution Engine 253 7.1.11 Merger Engine 256 Iteration Merger 257 Order-by Merger 257 Group-by Merger 259 Aggregation Merger 262 Pagination Merger 262 7.2 Transaction 309 7.7.21 21. [Other] Why does Oracle database throw "Order by value must implement Comparable" exception when using Timestamp Order By? 309 7.7.22 22. [Other] In Windows environment, when cloning ts/f/9/d/d/f9ddf8ef480b3130781b7087837e640e/p24_1.jpg) ### 3.2 Mode #### 3.2.1 Background In order to meet the different needs of users for quick test startup, stand-alone running and cluster running

495 /metadata/{databaseName}/rules/sharding/tables/t_order/versions/0 ..... 496 /metadata/databaseName/schemas/{schemaName}/tables/t_order/versions/0 ..... 496 /nodes/compute_nodes ..... 497 Automatic Execution Engine ..... 517 12.4.11 Merger Engine ..... 521 Traversal Merger ..... 521 Order-by Merger ..... 521 Group-by Merger ..... 523 Aggregation Merger ..... 526 Pagination Merger into different databases. The diagram below has presented the solution to assign user tables and order tables to different databases by vertical sharding according to business need. ![Image](/uploads

/metadata/ $ {databaseName} $ /rules/sharding/tables/t_order/versions/0 ..... 460 /metadata/databaseName/schemas/ $ {schemaName} $ /tables/t_order/versions/0 ..... 460 /nodes/compute_nodes ..... 461 6.3 其他使用 SQLSever 和 PostgreSQL 时，聚合列不加别名会抛异常？511 13.6.4 其他 Oracle 数据库使用 Timestamp 类型的 Order By 语句抛出异常提示 “Order by value must implement Comparable”？512 13.6.5 其他 Windows 环境下，通过 Git 克隆 ShardingSphere 相同结构的水平拆分数据库（表）的逻辑名称，是 SQL 中表的逻辑标识。例：订单数据根据主键尾数拆分为 10 张表，分别是 t_order_0 到 t_order_9，他们的逻辑表名为 t_order。 ## 真实表 在水平拆分的数据库中真实存在的物理表。即上个示例中的 $ t_{order\_0} $ 到 $ t_{order\_9} $ 。 ## 绑定表 指分片规则一致的一组分片表。使用绑定表进行多表关联查询时，必

/metadata/ $ {databaseName} $ /rules/sharding/tables/t_order/versions/0 …… 486 /metadata/databaseName/schemas/ $ {schemaName} $ /tables/t_order/versions/0 …… 486 /nodes/compute_nodes …… 487 /nod 13.6.3 其他使用 SQLSever 和 PostgreSQL 时，聚合列不加别名会抛异常？ 13.6.4 其他 Oracle 数据库使用 Timestamp 类型的 Order By 语句抛出异常提示 “Order by value must implement Comparable”？ 13.6.5 其他 Windows 环境下，通过 Git 克隆 ShardingSphere 源码时为什么提示文件名过长，如何解决？ 相同结构的水平拆分数据库（表）的逻辑名称，是 SQL 中表的逻辑标识。例：订单数据根据主键尾数拆分为 10 张表，分别是 t_order_0 到 t_order_9，他们的逻辑表名为 t_order。 ## 真实表 在水平拆分的数据库中真实存在的物理表。即上个示例中的 $ t_{order\_0} $ 到 $ t_{order\_9} $ 。 ## 绑定表 指分片规则一致的一组分片表。使用绑定表进行多表关联查询时，必

Connection Mode 377 Automatic Execution Engine 378 7.4.11 Merger Engine 382 Traversal Merger 382 Order-by Merger 382 Group-by Merger 384 Aggregation Merger 387 Pagination Merger 387 7.5 Transaction 461 8.6.4 Other Why does Oracle database throw "Order by value must implements Com parable" exception when using Timestamp Order By? 461 8.6.5 Other In Windows environment, when cloning into different databases. The diagram below has presented the solution to assign user tables and order tables to different databases by vertical sharding according to business need. ![Image](/uploads

Automatic Execution Engine ..... 405 7.4.11 Merger Engine ..... 409 Traversal Merger ..... 409 Order-by Merger ..... 409 Group-by Merger ..... 411 Aggregation Merger ..... 414 Pagination Merger into different databases. The diagram below has presented the solution to assign user tables and order tables to different databases by vertical sharding according to business need. ![Image](/uploads data sharding modular of Apache ShardingSphere is to try to reduce the influence of sharding, in order to let users use horizontal sharding database group like one database. #### 3.1.4 Application Scenarios

Automatic Execution Engine ..... 274 7.2.11 Merger Engine ..... 277 Iteration Merger ..... 278 Order-by Merger ..... 278 Group-by Merger ..... 280 Aggregation Merger ..... 283 Pagination Merger . 364 7.8.24 [Other] Why does Oracle database throw "Order by value must implement Comparable" exception when using Timestamp Order By? . 364 7.8.25 [Other] In Windows environment, when cloning ts/1/8/e/e/18ee40b6b24bd0759642fb22897914fe/p26_1.jpg) ### 3.2 Mode #### 3.2.1 Background In order to meet the different needs of users for quick test startup, stand-alone running and cluster running