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 transactio
DbVisualizer presents the plan either in a tree style format or in a graph, or in a simple text format. What information is shown depends on the database you use. In the tree view, put the mouse pointer on the column header for a tooltip description what that column represents. The fol...
2.filter --过滤,如not in、min函数等容易产生 Has a number of different meanings, used to indicate partition elimination, may also indicate an actual filter step where one row source is filtering, another, functions such as min may introduce filter steps into query plans. 3.view --视图,大都...
2.filter --过滤,如not in、min函数等容易产生 Has a number of different meanings, used to indicate partition elimination, may also indicate an actual filter step where one row source is filtering, another, functions such as min may introduce filter steps into query plans. 3.view --视图,大都...
Explain plan is a feature that allows you to see a visual representation of the execution plan of a query in a tree or table format. When you execute your queries in the query window and the execution plan is available, you can view the plan under the 'Plan' tab. This feature is usef...
To view the EXPLAIN PLAN for this query, use the command: EXPLAIN PLAN FOR select /*+ result_cache */ deptno, avg(sal) from emp group by deptno; select PLAN_TABLE_OUTPUT from TABLE (DBMS_XPLAN.DISPLAY()); The EXPLAIN PLAN output for this query should look similar to the following...
[转]Oracle执行计划（ExplainPlan）说明 [转]Oracle执⾏计划（ExplainPlan）说明 原⽂地址:http://langgufu.iteye.com/blog/2158163 如果要分析某条SQL的性能问题，通常我们要先看SQL的执⾏计划，看看SQL的每⼀步执⾏是否存在问题。如果⼀条SQL平时执⾏的好好的，却有⼀天突然性能很差，如果排除了...
1.Using the Explain Plan statement in SQL To use the Explain Plan statement in SQL, the query must first be prepared and then the Explain Plan statement is run. After the Explain Plan statement is executed, a query is run to view the Explain Plan output. 2.Using the GUI-based DBMS_XPL...
stalera Apr 3rd, 2010 Disabling the view state wherever necessary, having ajax play its role, removal of unnecessary controls. storing view state at server side if the view state is very heavy. Was this answer useful? Yes ReplyRelated Answered Questions...
FORMAT VARCHAR2IN FORMAT_FLAGS BINARY_INTEGEROUT SQL> 2. Column Projections 所谓column projections就是指DBMS_XPLAN给出的信息中包含了SQL执行计划中每一步实际选择的列的信息,这个有助于我们理解SQL执行计划每一步的实际动作。 以Scott中的表作为例子, ...