Database Administrator

1) One of the key points to solve the GoldenGate error is to use the error analysis tool, including the report file, the logdump tool of the ggserr. log discard file, and the GGSCI command line) to determine which component causes the error. System

1. If the AUTO_INCREMENT field exists in the mysql table, the AUTO_INCREMENT field will not be automatically initialized to 0 after the data is cleared (delete from), but will still start auto-increment after the records are cleared, manual

Create table a (no number notnull, name varchar (10) notnull, loc varchar (10) notnull ); Create table B (no number notnull, name varchar (10) notnull, loc varchar (10) notnull ); Insert into a values (10, 'aaa', 'aremak1 '); Insert into a values (2

When you restore a database, you often encounter errors that cannot be restored successfully. Common Errors are as follows: Message 5070 cannot change the database status when other users officially use the database "" This error occurs

Ora-02292: Username that violates the complete constraints. constraint name)-The subrecord has been found. Another reason is that A field in Table B references A field in Table A as A constraint ). If the referenced field is field and B. field is

Chapter 4 Hadoop I/O1) IntegrityHDFS transparently checksums all data written to it and by default verifies checksums when reading data. the default is 512 bytes, and because a CRC-32 checksum is 4 bytes long, the storage overhead is less than 1%.

All characters with n are unicode encoded, and letters and Chinese characters are in 2 bytes. Char fixed length. The varchar length is not fixed. Differences between char and varchar: The char type in the database is used to store fixed-length

I. Installation Process1. Download libevent-2.0.12-stable and compile and install wget http://httpsqs.googlecode.com/files/libevent-2.0.12-stable.tar.gztar zxvf libevent-2.0.12-stable.tar.gzcd libevent-2.0.12-stable/./configure

/Usr/local/webserver/mysql/bin/mysqldumpslow-s r-t 20/data0/mysql_data/slowquery. log /Usr/local/webserver/mysql/bin/mysqldumpslow-s c-t 20/data0/mysql_data/slowquery. log The preceding command shows the 20 most frequently accessed SQL statements

1. Shell defines the order of user environments 1)/etc/profile The template profile file defined by the Super User applies to every user. 2)/etc/enviroment The template profile file defined by the Super User applies to every user, but only in

1. Checkpoints Checkpoints checkpoint is the system powered on CMOS initialization program initial program load, IPL) after running, a series of information is displayed on the display panel of the I/O cabinet. After the AC power supply is

Database backup and recovery:Note:For oracle databases installed on windows, when using the exp BACKUP command, enter the bin directory in dos.For oracle databases installed on linux, after environment variables are configured, they can be directly

The startup process includes the following steps: The initial step for starting a system is Power-On Self-check Power On Self Test, POST ). The purpose is to verify whether the basic hardware is working properly. Initialize the memory, keyboard,

AIX: 1. Obtain the Optical Fiber Device connected to the AIX Host: # Lsdev-Cc adapter-S a | grep fcs Fcs0 Available 09-08 FC Adapter Fcs1 Available 09-09 FC Adapter Two Optical Fiber cards are displayed. Fcs0 and fcs1 2. view the WWN Number of the

Http://boylook.itpub.net/post/43144/520544 As we all know, Oracle locks are row-level. Let's take a look at Oracle's Secure Access Mechanism:Secure Data Filtering must be completed at the first layer of the basic data table, so that users cannot

Looking back at the CASE of online database (5.1.68), a large number of thread_running occurs during the peak period. It is found that the thread is in the deadlock State and only one table is involved, and there is only one row: Table ('Id'

Http://boylook.itpub.net/post/43144/520546 Cast table:A ------ boylookB ------ hrC ------ davidSQL> show userUSER is "BOYLOOK"SQL> select * from tab;TNAME TABTYPE CLUSTERID-----------------------------------------------USERENV VIEWTEST_REFED

Two hosts Hostname: linux-web ip: 10.5.5.23 Hostname: linux-mysql ip: 10.5.5.27 Host1: linux-web Vim/etc/my. cnf Server-id = 1 Log-bin = master-bin Master-host = 10.5.5.27 # hostname linux-mysql Master-user = slave # The

I. Files and file groups 650) this. width = 650; "title =" file group .png "src =" http://www.bkjia.com/uploads/allimg/131229/210HHa5-0.png "alt =" 111522649.png"/> In the same file group, multiple data files act as Server Load balancer. Therefore,

1. Redis memory storage structure This article is based on the Redis-v2.2.4 version for analysis.1.1 overall Redis memory storage structure Redis supports multiple key-value databases (tables) and uses RedisDb to represent a key-value database