Oracle

Oracle tablespaces, Data files, and each user's Oracle database are composed of three types of files: Data files, Log files, and Control files ). Database files provide real physical storage for database information.Each database has one or more

Recently, a large volume of data in oracle tables needs to be deleted due to slow queries and updates. It is found that the query speed after deletion is still very slow. It turns out that the high watermark of delete oracle has not declined. In

Plsql cannot connect to the oracle server in linux. Recently, when the company was down, it was found that after oracle data and listening programs in linux started normally, plsql on the client still could not connect to the server, ORA-12514 error

Oracle 10g rac listener name: CRS-0210: cocould not find resource problem want to restart the listener, The results found that the [oracle @ node1 ~] $ Srvctl stop listener-n node1CRS-0210: cocould not find resource ora. node1.LISTENER _ NODE1.lsnr.

Compared with IN & EXISTS in Oracle SQL, IN and exists are sometimes used to retrieve data in Oracle SQL. What is the difference between them? 1 Performance Comparison: for example, the execution process of Select * from T1 where x in (select y from

There are two simple examples of exists and not exists usage in oracle to illustrate the efficiency of "exists" and "in". 1) select * from T1 where exists (select 1 from T2 where T1.a = T2.a); T1 has a small amount of data, while T2 has a large

Time-based backup retention policy rman study 1 Experiment Preparation a) physical and logical checks [SQL] SQL> col file_name for a70 wrapped SQL> select file_name, status from dba_data_files where file_id = 4; FILE_NAME STATUS certificate ---------

Oracle client configuration 1. copy the client file and copy the instantclient_11_2 folder to a directory. I put it on drive D directly. 2. configure the client environment variable TNS_ADMIND: \ instantclient_11_2 3. configure the sid file

Oracle RAC connects to a specified instance. In some specific cases, you sometimes need to connect to the specified instance in RAC from the client, instead of dynamically selecting the client Load_balance or forwarding it based on the load

In Oracle, how can I use SQL to check whether the field contains Chinese Characters? Today, a colleague's data migration program has a problem. I didn't consider Chinese encoding characters. Because the migrated table has tens of millions of data,

The Oracle bitmap index assumes that a table with rows has a field that is frequently used as a query condition. We will create an index on this column. However, this column may only have three values. If a B * tree index (Common Index) is created,

High-efficiency optimization of Oracle SQL statements many people seem to know little about SQL optimization. Recently I have summarized several articles for your reference only. However, a few of them may depend on the situation, most of them are

The NVL, NVL2, NULLIF, and COALESCE functions in oracle are used to apply the string processing penalty, date functions, mathematical functions, and conversion functions previously introduced in Oracle. A type of function is a common function. The

Oracle Database migration may occur during the project, so the sequence may be reset, resulting in the current value of the sequence.When it is less than the maximum value of the field in the table that uses the sequence, an error occurs,

Oracle 10 Gb extended tablespace 1. manually add the data file size www.2cto.com alter database datafile 'C: \ oracle \ product \ 10.2.0 \ oradata \ CC_DB \****. dbf'resize 100 M; 2. set the tablespace to automatically expand alter database datafile

Common SQL statements for Oracle Database permission management 1. Three default users in Oracle9g: www.2cto.com username and password sys change_on_install [as sysdba] system manager scott tiger 2. User Logon 1) enable listening C: \ Users \

An error occurred when executing the flash back in oracle. I accidentally changed the password of another user in a user table in the database one day. When I want to help him back up, I will know that I forgot to back up www.2cto.com. At this time,

Oracle users cannot be deleted, and the system prompts "unable to delete connected users" 1. alter user XXX account lock; SELECT * from v $ session where username = 'lgdb'; alter system kill session 'xx, xx' drop user xx cascade 2. or shut down the

When ORACLE fails to delete the current connected user and solves the problem of deleting the user in Oracle, the following message is displayed: ORACLE cannot delete the current connected user www.2cto.com. You can use the following statement to

Oracle deadlock query and handling I. Database deadlock phenomenon during execution of the www.2cto.com program, click OK or save. The program does not respond or reports an error.Ii. deadlock principle when an update or delete operation is