When a view cannot be merged into the main query you will often see a projection view operation. This indicates that the 'view' will be selected from directly as opposed to being broken down into joins on the base tables. A number of constructs make a view non mergeable. Inline views ar...
DBMS_XPLAN最先是在Oracle9.2中引入的,但是只能用来查看SQL的“理论”上的执行计划(Explain plan for的结果), 在10g中,可以通过新增加的DISPLAY_CURSOR来得到SQL(CURSOR)的“实际”执行计划信息。 (Tom 在<Effective Oracle by Design> 中提到如何在10g之前如何用DBMS_XPLAN.DISPLAY和V$SQL来得到实际执行的信息,下面...
Partition views are a legacy technology that were superceded by the partitioning option. This section of the article is provided as reference for such legacy systems. 附:oracle优化器(Optimizer) Oracle 数据库中优化器(Optimizer)是SQL分析和执行的优化工具,它负责指定SQL的执行计划,也就是它负责保证SQL执...
or in a simple text format. What information is shown depends on the database you use. In the tree view, put the mouse pointer on the column header for a tooltip description what that column represents. The following screenshot shows the SQL in the editor at top and the corresponding exp...
Oracle10g\11g中,如果我们对目标SQL执行explain plan命令,则oracle就将解析目标SQL所产生的执行计划的具体执行步骤写入PLAN_TABLE,随后执行select∗fromtable(dbmsxplan.display),只是从PLANTABLE,随后执行select∗fromtable(dbmsxplan.display),只是从PLANTABLE中将这些具体执行步骤以格式化的方式显示出来。
>>Note the drop-down control added to the Explain Plan button in the worksheet toolbar. This is a total disaster. Please make an option to disable this “feature” or just disable it. This “feature” blocks using dbms_xplan. I typically use gather_plan_statistics hint and select * fro...
12.1.3.1 Using V$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...
If you don't name the query blocks in a statement, Oracle will generate query block names for you. To see those names automatically, run an EXPLAIN PLAN on your statement followed by a query using the ALL option of DBMS_XPLAN.DISPLAY: ...
Explain an SQL query and store the obtained execution plan in thetesttable. /* Create a table named test. */ obclient> CREATE TABLE test (statement_id VARCHAR(30), plan_id INT, gmt_create TIMESTAMP, remarks VARCHAR(4000), operator VARCHAR(255), options VARCHAR(255), object_node VARCHAR...
In this article, we are going to learn about the different sorting techniques and their implementations in C language. Sorting in C programming requires rearranging elements in the array into a determined order, i.e., in ascending or descending order. This will use the comparison operator to ...