Database Administrator

I. Nullable When designing a table, a column is sometimes allowed to use the default Null value ). 650) this. width = 650; "src =" http://www.bkjia.com/uploads/allimg/131229/211U45539-0.png "title =" null.png "alt =" 110227268.png"/>

I. Overview MySQL has three levels of locks: Page, table, and row. The MyISAM and MEMORY storage engines use table-level locking. The BDB storage engine uses page-level locking, but also supports table-level locking; the InnoDB Storage engine

Hive is engaged in the Query Platform for each Query tag, want to try the effect if found that there is no data inflows; the original found Hive inside made an improvement: https://issues.apache.org/jira/browse/HIVE-887 For simple queries, instead

Recently, we are looking at oracle recovery and backup mechanisms. It is fresh to learn about oracle beginbackup and endbackup. I did some small experiments. The result is confused. I don't know why I need this technology. Sys @ CISCOSYS> alter

-- ================================== -- SYSTEM tablespace management and Backup Recovery -- ================================== SYSTEM tablespace is the most important tablespace in Oracle databases. It stores information generated by some DDL

In the morning, I saw two dead Datanode alarms. I checked the system logs and found that the current high load caused the datanode to time out and the heartbeat was removed by DatanodeManager, further found that the high load is caused by a Job with

Mysql hot standby1. Check the mysql version to ensure that the master database is less than or equal to the slave Database2 master Database Configuration:A needs to enable the log support function: log-bin = mysql-binB provides server-id: server-id =

Idle> startup ASM instance started Total System Global Area 83886080 bytes Fixed Size 1217836 bytes Variable Size 57502420 bytes ASM Cache 25165824 bytes ORA-15032: not all alterations saved med ORA-15063: ASM discovered an insufficient number of

(I) Management Principles of ASM disk groups ① Impact of adding or deleting a disk When a disk is added or deleted from a disk group, ASM can automatically balance the disk. For normal delete operations (without the force option), the deleted disk

/* 1. Use some, any, and all to process the multiple rows returned by the subquery. 1. some satisfies the meaning of one of them here, which is a comparative clause concatenated with or. 2. any also indicates satisfying one of the meanings. It is

Today, I accidentally found an error message in master-slave synchronization. 650) this. width = 650; "src =" http://www.bkjia.com/uploads/allimg/131229/20333140S-0.jpg "title =" qq 30929160030.jpg "alt =" 160108925.jpg"/> follow this method to fix

I. Session-based temporary tables -- To create a session-based temporary table, remember the global temporary keyword and on commit preserve rows (Session-based) Create global temporary table TEMP_SESSION (COL1 TYPE1) on commit preserve rows; SQL>

As we all know, myisam is a table-Level Lock! It can provide fast queries, but there are more than one update, and myisam table-level locks lead to extremely slow queries! Some applications suffer from the need to use fulltext and cannot change the

Job functions:Database Engineer/Administrator Job description:Responsibilities:Continuous Configuration and optimization of database managementManage and support large Oracle Database SystemsMonitors online database systems and responds to

10.1 perform the huge table splite to partition table action. The process went smoothly. After the program was started, it was found that some reporting programs were slow. The analysis shows that the number of sessions is high, and the active

Working topology: 650) this. length = 650; "src =" http://www.bkjia.com/uploads/allimg/131229/201Z26336-0.jpg "title =" mysql-master-salve-proxy.jpg "width =" 400 "height =" 354 "border =" 0 "hspace =" 0 "vspace =" 0 "style =" width: 400px; height: 3

Official: The first time you install Oracle Database software on a server, you are prompted to specify the location of the inventory directory, called oraInventory. this directory provides a centralized inventory of all Oracle software products

If you use INFOBRIGHT, you will not be familiar with this word.There are currently four formats. 1. binary.2. txt_variable3. mysql4. infobright What does it mean? Let me explain it in detail.BINARY represents BINARY data. That is to say, raw data

In ORACLE 11gR2, the installation of RAC has changed significantly. In the age of 10 GB and 11gR1, the procedure for installing RAC is to first install CRS and then install DB. In the age of 11gR2, crs and asm are integrated and collectively called

ORA-12545 Errors often occur when a remote client connects to the RAC database over a uniform service name. After querying METALINK, it was a small bug in Oracle.Environment: ORACLE 11G R2 RAC database, two nodes.Symptom:[Oracle @ ted35 ~] $ Sqlplus/