Database Administrator

This chapter describes the logical Storage Structure and relationships of Oracle databases, including the following:1. Introduction to data block, extent, and segmentIi. Data Block overviewIii. Overview of ExtentIv. Segment OverviewI.

Background: Recently, I encountered a very BT project where I used the image disk array of the database for RMAN backup. Archive logs generated in the production environment need to be cleared regularly. In addition, because the image disk array is

When you delete data from a table, the following error occurs: ORA-02292: Full constraint condition (UNITELE. ta_sub_referene3)-subrecord found ". If the table already has a primary key, the primary key constraint is invalid. Alter table table_name

Oracle all_parameters view create SQL  /* Formatted on 17:06:07 (QP5 v5.114.809.3010 )*/ Create view all_parameters AS SELECT I. ksppinm name, I. ksppdesc description, CV. ksppstvl VALUE, CV. ksppstdf isdefault, DECODE (BITAND (CV. ksppstvf, 7 ), 1,

Oracle time format conversion Exception Handling Function Create Or Replace FunctionF_FORMAT_DATE (v_date varchar2, formatVarchar) /* Time Format processing format */ Return Date As V_endDateDate; V_rn varchar2 (2 ); V_LAST_DATE

Set the primary usage of Mysql master-slave replication:1. If the master server crashes, the slave server can be directly enabled as the master server.2. You can directly lock the table read-only from the server and back up the data without

FirstGo to the Oracle official website to download the C language library file and header file URL as follows, select the corresponding Instant Client Version (I downloaded all zip packages without downloading the rpm package, the rpm package should

In Oracle 11g, in order to allow the customer to change the password of the database user within six months, the default password of the database user is valid for 180 days by default, oracle 10 Gb default database user password is no time. View

Procedure: 1. Create a temporary tablespace for transit 2. Delete the original temporary tablespace 3. re-create it. Operation Command: Create a temporary tablespace Create temporary tablespace temp2 Tempfile '/u01/oradata/orcl/temp02.dbf'

Restore data files in the system tablespaceThe system tablespace stores the data dictionary information. When the database is in the open state and the data file corresponding to the system tablespace fails, the database will automatically shut down

By default, MongoDB does not need to enter the User and password, so the client can log on. This security problem is serious. There are also many examples on the Internet, but there are also many details that many people have not noticed me here by

In exp and imp, there is no syntax for exporting only stored procedures. If a user's data is exported, all objects (tables, views, indexes, sequences, functions, stored procedures, triggers, etc.) of the user will be exported ). If only all stored

Select * From (Select RowNum field_ByName, d. * From (SELECT B. *, c. loginaccount from jitums. TB_READERS B, JITUMS. tb_rd_account c where B. reader_id = c. reader_id) d Where RowNum = 1; Select * From (Select RowNum field_ByName, B. * From

Note that Ubuntu 11.04 MySQL 5.1 is used. Windows estimates are different .. Study for yourself !! 1. It is not recommended to use the BACKUP and RESTORE commands after logging on to MySQL. Later versions may be removed .. So stop using it! 2. Use

Note that in Linux bash, this is certainly not supported in Windows .. However, you can try to write a bat batch file to achieve the same effect! To run the mysql file,If you have logged on to mysql, you can directly run: source filename. SQL In the

I. Description A netizen asked me to store a query result set to the temporary table. If I estimated the size of the temporary table, I wanted to calculate it through the statistical block. Later I thought that this method was not very operational.

MysqlExecution Process: MysqlIt is a single-process service, and every request is responded by a thread. This requires a connector to handle new user requests, responses, and destruction. 1.Client request, server (connector) opens thread to respond

Basic Linux operations Uname-r view kernel version Df-m to view the space of each storage device Du-sh: view the current directory space size View processes and IO: top, mpstat-p all 1 100, iostat-x 1 10 (test IO performance) Force Delete the rm-rf

1. Concept of an instance An instance is an Oracle software in the running state, mainly composed of a memory structure and some processes. In Oracle, each database has at least one corresponding instance. A single instance can only open and use one

These background processes are optional and can be selected based on your needs. They provide some tools, but these tools are not required to run the database every day, unless you want to use them yourself (such as Job Queue ), Or you need to use