EXPLAIN 语句返回的结果会显示视图引用的表和索引,而不是视图本身的名称。这是因为视图是一张虚拟表,本身并不存储任何数据。视图的定义会和查询语句的其余部分在 SQL 优化过程中进行合并。 参考bikeshare 数据库示例(英文),以下两个示例查询的执行方式类似: ...
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...
They are used to evaluate execution plan that SAP HANA database follows to execute the SQL statements.The results of explain plan are stored into EXPLAIN_PLAN_TABLE for evaluation. To use Explain Plan, passed SQL query must be a data manipulation language (DML)....
Breadcrumbs docs-cn / explain-views.mdTop File metadata and controls Preview Code Blame 119 lines (95 loc) · 8.61 KB Raw titlesummary 用EXPLAIN 查看带视图的 SQL 执行计划 了解TiDB 中视图相关语句的执行计划。用EXPLAIN 查看带视图的 SQL 执行计划EXPLAIN...
In previous articles I shown that in both Oracle and SQL Server, the second method (two LEFT JOINs) is more efficient to query poorly localized languages, while for well-localized languages the third query should be used, i. e. a LEFT JOIN for the local language and a subquery for the ...
Oracle Database provides information on cached cursors through several dynamic performance views: For information on the work areas used by SQL cursors, queryV$SQL_WORKAREA. For information on the execution plan for a cached cursor, queryV$SQL_PLAN. ...
12.1.3.1 Using V$SQL_PLAN Views In addition to running the EXPLAIN PLAN command and displaying the plan, you can use the V$SQL_PLAN views to display the execution plan of a SQL statement: After the statement has executed, you can display the plan by querying the V$SQL_PLAN view. V$SQL...
What is the difference between database manipulation language and database definition language? Databases can have various objects, some of which are tables, queries, forms, and views. Each of these has fields or columns. Describe the function of each ...
I get a spill error when i paste =UNIQUE(RANDARRAY(100,1,9788723527370120,9788723527370990,TRUE)) in a clean sheet at a1 cell. Am i doing something wrong? Ohayonson No, it appears to be a bug. Paste the formula into any other cell - it should work. ...
The following language elements may not be used: BETWEEN, LIKE, IN. No sub-queries may be used. For outer joins, only equality comparisons (=, EQ) are possible. If an outer join occurs after FROM, the join condition of every join expression must contain at least one comparison between co...