the concept “transaction“ of DBMS and the explain the five states of a transaction. 技术标签:考研 构成单一逻辑工作单元的操作集合称作事务 事务必须处于以下五状态之一: 活动的(active):初始状态,事务执行时处于这个状态。 部分提交的(partially committed):最后一条语句
ClickHouse是俄罗斯的Yandex于2016年开源的列式存储数据库(DBMS),使用C++语言编写,主要用于在线分析处理查询(OLAP),能够使用SQL查询实时生成分析数据报告。 OLAP(On-Line Analytical Processing)翻译为联机分析处理,专注于分析处理,从对数据库操作来看,OLAP是对数据的查询; OLTP(on-line transaction processing)翻译为联机...
REBUILD. EXPLAIN for the rest of MySQL statements may be implemented in separated WLs by request. There is no intent to support EXPLAIN for table-maintenance, data-description-language, transaction-control, backup-restore, utility, or non-preparable statements....
Introduced in 7.3 and requires V733_PLANS_ENABLED=TRUE and CBO, may be hinted using INDEX_FFS hint, uses multiblock i/o, can be executed in parallel, can be used to access second column of concatenated indexes. This is because we are selecting all of the index. ...
If you do not specify INTO table_name, the execution plan is stored in the PLAN_TABLE table by default. SET statement_id The statement ID of the explained SQL statement, which can be used to query the execution plan of the statement later. If you do not specify SET statement_id, an ...
SQL>SELECT plan_table_output FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE')); 示例: SQL>EXPLAIN PLAN FOR SELECT * FROM DAVE; 已解释。 SQL>SELECT plan_table_output FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE')); 或者: SQL>select * from table(dbms_xplan.display); ...
This means for a given SQL or DML statement the execution plan that was used for the last execution will be shown. The following matrix shows what type of execution plan you can see in which transaction for the different databases: Database (SAP name) ST05 ST04 DB2 estimated execution ...
It would be more efficient to drive from the TRANSACTION table because there are no limiting conditions on the customer table. The database would join rows from the TRANSACTION table to the ACCOUNT table, and finally to the CUSTOMER table. In this case, the indexes used on the ACCOUNT and ...
Yes, it is possible to run analytics on at OLTP database as online transaction processing includes a real-time analytic. Analytics is a type of...Become a member and unlock all Study Answers Start today. Try it now Create an account Ask a question Our experts can answer your tough...
Why is synchronization a problem in data communication? Which of the following will cause a deadlock? A. Transaction T1 requests an exclusive lock on data A at the same time as transaction T2. B. Transaction T1 places an exclusive lock on data A, then transaction T2 requests a...