Query 和Current 的总和为所访问的逻辑缓冲区的总数 执行下面命令:tkprof D:\ORACLE\PRODUCT\10.2.0\DB_1\RDBMS\TRACE/wgods_ora_3940.trc h:\out.txtoutputfile explain=etl/etl 执行上面命令后,可以查看生成的文本文件 复制代码 代码如下: TKPROF: Release 10.2.0.1.0 - Production on 星期三 5月 23 16:...
Oracle 执行计划(Explain Plan) 说明 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,如果排除了系统资源和阻塞的原因,那么基本可以断定是执行计划出了问题。 看懂执行计划也就成了SQL优化的先决条件。这里的SQL优化...
Action: Connect to the database as a user with SYSDBA privileges. Execute the ORACLE_HOME/rdbms/admin/initqsma.sql script. QSM-01001 query rewrite not enabled Cause: When query rewrite is disabled, no query rewrite will take place. Action: Enable query rewrite with ALTER SESSION SET QUERY_...
General application incompatibility—This reason is a somewhat of a catch-all. For example, Azure SQL Database doesn't support cross-database querying, while managed instance does. Some applications require other services to coexist with the database instance in a manner that i...
Why do we need an associative table for many-to-many relationships? The UNIQUE constraint differs from the PRIMARY KEY constraint in what way? What is the purpose of a database, and how does the database accomplish this purpose? What is a RDBMS ...
For example, start a SQL*Plus session, connect with SYSDBA privileges, and run the script as follows: @$ORACLE_HOME/rdbms/admin/catplan.sql Oracle recommends that you drop and rebuild your local PLAN_TABLE table after upgrading the version of the database because the columns might change. ...
• Object Databases:These days OOP concepts have also been introduced indatabasesystems to develop a newDBMSnamed object databases. These databases store the data directly in the form of objects. However, these databases are not as popular as the traditional RDBMS. ...
You will find a script called utlxplan.sql in $ORACLE_HOME/rdbms/admin that creates a plan table with the name plan_table in the local schema. If you use this script to create your plan table, you can be assured that the table will have the right definition for use with EXPLAIN PLAN...
在RDBMS中,无论那种数据库,都提供了SQL剖析工具,用来解决SQL效率低下的问题。在MongoDB中,也有相应的策略来实现剖析。MongoDB提供了db.collection.explain()方法, cursor.explain()方法,和explain命令去返回查询计划信息和查询计划的执行统计信息。这为我们诊断查询提供了极大的便利,本文主要描述db.collection.explain()...
I created a user MNASH and created a PLAN_TABLE in MNASH’s schema using $ORACLE_HOME/rdbms/admin/utlxplan.sql. This was in addition to the PUBLIC synonym PLAN_TABLE for the SYS.PLAN_TABLE$ temporary table created by default. SQL> explain plan for ...