Oracle

1, the role of statistical information Oracle's CBO optimizer relies heavily on statistics when generating execution plans, you can interpret the CBO as a complex mathematical model, and statistics is its primary input, the execution plan is output,

First, let's talk about what they have in common: they are essentially exclusive locks on resources that are caused by concurrency (if the database has only one session, it's not locked). Then focus on the different points: First of all, their

--New test table Create Tablespace Test DataFile ' E:\APP\ADMINISTRATOR\ORADATA\ORCL\test01. DBF ' Size 500m Autoextend on Next 100m MaxSize Unlimited Extent Management Local Autoallocate Segment Space management auto; CREATE TABLE T1 (

1, monitoring channels: summed up mainly through two aspects to carry out: 2, monitor the progress of recovery (1) View the active state of the process The V$managed_standby view is dedicated to displaying the current state of a physical

Conn System/manager ----------------------------Create a user, assign quotas, and create a table--------------------- DROP USER test2 CASCADE; Create user test2 identified by Test2; Select Username,password,profile,default_tablespace from

In order to do this experiment I first create a user, user name: 111 Password: 111 Sql> create user identified by 111; User created. Sql> Grant connect to 111; Grant succeeded. Test on the client link $ sqlplus 111/111 Sql> select Sysdate

There is a problem that has been puzzling for a long time, in case of a failure when upgrading CRS. The RAC is a joke that can't be easily opened. This test is done on the Linux platform, and the production library operations need to be cautious. 1

A system that, after a long period of operation, maintenance, and versioning, may produce a large number of indexes, even though the index occupies far more space than the data. Many indexes are useful for systems in the initial design. However,

--View the low-efficiency SQL method as follows Select A.sql_text, A.executions, A.disk_reads, A.buffer_gets, Round ((a.buffer_gets-a.disk_reads)/a.disk_reads,2) Hit_radio, Round (a.disk_reads/a.executions,2) Read_per_run From V$sqlarea A

/* Before creating a tablespace under the server directory/optoracle/oradata/etld, manually build the Etld directory and use root to give the Etld directory the appropriate permissions, such as 777 */ --Create a table space Create Tablespace Tbs_

Test Table name: D 1, to determine whether a table has been analyzed: Select T.num_rows,t.avg_row_len from User_tables t where T.table_name = ' D ', If the result is empty, it means that the table has not been parsed; 2, the table has not been

Application Scenario: Large data --1), create a partition table CREATE Table A (Statis_date varchar2 (8), ID number, Name VARCHAR2 (50), Salary number ) Partition by list (statis_date) (Partition day_20121130 values (' 20121130 '),

Today, a friend asked, if the time is calculated, such as a time value plus 3 minutes, or a time minus 1 seconds. The following tests briefly illustrate how such operations are used: Sql> alter session set nls_date_format= ' Yyyy-mm-dd hh24:mi:ss '

1. RAID definition RAID, full name Redundant array of inexpensive disks, Chinese name is redundant array of inexpensive disks. RAID can be divided into soft raid and hard raid, soft raid is the software to achieve multiple hard disk redundancy.

List of common commands summary memo The list command lists the control files and the backup information in the Rman recovery directory, which is one of the most intuitive ways to understand all of the visible database backup files. List

One, the source side Add extract Extl,tranlog,begin Now ADD EXTTRAIL/U01/OGG/DIRDAT/LR, EXTRACT EXTL ADD Trandata chf.objce_t Edit params EXTL Extract EXTL UserID Ogg,password Xifenfei Exttrail/u01/ogg/dirdat/lr Dynamicresolution

1, the installation of Oracle transparent gateway transparent gateways.Install Oracle Select Custom Install, then select Install transparent gateway, then go in to choose the component that installs for SQL Server.2. Modify

It is time-consuming to perform data manipulation language (DML) in a pl/sql loop because each loop is diverted from the Pl/sql engine to the SQL engine. Applying ForAll is a better way to submit a set of temporary values to a SQL statement at a one-

Oracle provides a variety of diagnostic tools for the RDBMS, and diagnostic events (event) is one of the common, easy-to-use methods that enable DBAs to easily dump database structures and track specific occurrences. The usual format and

MySQL: How to transfer millions data from Oracle to MySQLhttp://blog.csdn.net/hwhua1986/article/details/53257427Oracle to MySQL migration steps and a variety of considerationsHttp://www.2cto.com/database/201305/210248.htmlMySQL vs. Oracle diff data