Database Administrator

In many cases, DBAs need to perform operations that cannot be performed online. This statement is quite difficult. For example, if you add a column to a core-level table or perform a modification operation, not only will the master database lock the

I. Environment Description (using rsync for mysql Incremental Backup) 192.168.0.2 is the backup server. 192.168.0.3 is the mysql database that needs to be backed up frequently. Ii. Main Configuration 1. Backup Server ConfigurationUseradd

First, what will happen if Oracle is not uninstalled and then installed in Linux? In a production environment installation, an error occurs during Oracle installation, which leads to oracle Installation failure, ignore the previous installation and

Task Description: Copy all table space wy content to table space tietong. Procedure:1. First, install Oracle locally. 2. Use the Net Configuration Assistant to create a local Net service for the CMSTEST database in 10.153.246.149. the username and

Character Functions This function generally receives characters as parameters and can return characters or numbers. The following two functions are commonly used: 1. CONCAT Function It is mainly used for string connection. The specific syntax is as

After I restored the Deleted Data Based on scn last time, I felt that I should have a good understanding of the scn. Today I found some related introductions on the Internet and referred to some articles, here I will summarize the experiment. After

Now Oracle 11G has gradually matured, But oracle 10g is still king. Recently, many people on the Internet have not very familiar with rman catrman, so I hope to write it down to help them. Oracle's rman backup data includes: Catalog Database is a

Dynamic SQL syntax Only when running can Oracle check whether its format is correct The INTO and USING clauses are optional. If the SQL statement is a query statement, we can use the INTO clause. The INTO statement is used to receive the record

Sometimes a long character column needs to be indexed, which will make the index larger and slower. One policy is to simulate hash indexes. But sometimes this is not good enough, then? Generally, you can index the first few characters instead of

The Hash Index is based on the Hash table. It is only useful for exact search of each column in the Index. For each row, the storage engine calculates the indexed Hash Code, which is a small value and may be different from the Hash Code of other

Interaction between main modules (introduces the main responsibilities of various modules of mysql) When Connection Manager receives a Connection from the client, it initializes the network Connection process and establishes the Connection handler

1. Check whether the Oracle database master service and listener service are enabled2. Check whether the listener. ora file is correctly configured. SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = PLSExtProc) (ORACLE_HOME = G: \

View the redo log switching frequency of Oracle The two SQL statements have the same principle, and the second uses the statistical function. Time unit: minute Method 1,Select * from v $ log a where a. THREAD # = 1; Set line 200Select B. SEQUENCE #

Wildcard description _ Match with any single character % Matches a string that contains one or more characters. [] Matches any single character in a specific range (for example, [a-f]) or a specific set (for example, [abcdef. [^] Matches any

During daily use, hbase data in a cluster may need to be migrated to or copied to another cluster. At this time, many problems may occur. The following are some of my practices and handling methods in the process. Premise: the two hbase versions

I1. Start: the fields in the SQL code exported through powderDesiger are all in lower case and then directly imported to Oracle. 2. bug: The table structure cannot be modified (in PL/SQL Developer) --- including adding deletion and modification... 3.

Modifying the DATABASE spfile file in Oracle 11GR2 RAC is not the original $ ORACLE_HOME/dbs/init . ora file. If we manually modify this file, it will still take effect when SQL plus is used to manually start the database, but if we use srvctl or

When I interviewed mysqldba, I encountered a question: Describes the implementation principle of the msyql replication mechanism. How can I restore the database node of the slave with inconsistent data without stopping the mysql master

Oracle 11g changes the database to archivelog mode. There are three ways to set automatic archiving in ORACLE 10G: 1. When you use DBCA to install a database, configure it to the automatic archiving mode. You can enable automatic archiving after

I encountered a problem when I learned how to add Foreign keys to the database today. I first created two tables, orders and order_items. The storage engine is InnoDB and all of them have the orderid attribute (the same type), but I use the command