disk access

Recovery | data A "thrilling" data recovery experience Owlbird Cause A few days ago I was a database administrator when a friend called, his one database server can not start, make his head, and then ask people to look, they opened a 2000, no way

1. Hard drive Daily maintenance hard disk in the use of the process should pay attention to the following aspects: Computer work is strictly forbidden to move or collision machine, otherwise it may make the hard disk head and disc collision,

In the absence of any optimizations, every HTTP request, the Web server must read the requested page's data from the server's disk and send it to the client. The speed of disk access and its slowness relative to memory access speed (memory access

Excellent blog: The data structure and algorithm principle behind MySQL index B-Tree, B-tree, + + tree, b* tree "Turn", MySQL index The things about MySQL and B-trees The nature of the indexThe official MySQL definition

Database optimization:This optimization rule is summed up in 5 levels:1. Reduce data access (reduce disk access)2. Return less data (reduce network transmission or disk access)3. Reduce the number of interactions (reduce network transmission)4.

The main content of the article is divided into two parts.The first part mainly discusses the mathematical basis of MySQL database index from the data structure and algorithm theory level.The second part discusses the topics such as clustered

Memory database. As the name implies, put the data in the memory of the direct operation of the database.In contrast to disk, memory data reads and writes more than a few orders of magnitude, saving data in memory compared to on-disk access can

Database indexing is a sort of data structure in a database management system to assist in the quick querying and updating of database tables. The implementation of an index typically uses a B-tree and its variants, plus trees.In addition to data,

B-Tree (B-tree) is a balanced lookup tree designed for auxiliary access devices such as disk, which implements find, sequential read, insert, and delete operations with O (log n) time complexity . Because the B-tree and B-tree variants perform well

Original: The essence of HTTP://WWW.UML.ORG.CN/SJJM/201107145.ASP1 IndexThe official MySQL definition of an index is: index is the data structure that helps MySQL to get data efficiently. by extracting the skeleton of a sentence, you can get the

A detailed description of Linux file attributes:[Email protected] robin]# Ls-ihl/home/robin/test.txt398606-rw-r--r--. 1 root root 2315 Mar 21:00/home/test.txtThe columns correspond to the following explanations:Inode node Number file type

The general U disk fault is divided into soft faults and hard faults, of which the most common soft faults. Soft fault is mainly refers to a U disk has bad block, which can lead to a U disk to be recognized by the computer, but no letter appears,

This article is from the "Stones" blog, it is important to keep this source http://pengyl.blog.51cto.com/5591604/11789521, Linux on how to represent hard disk and partition hard disk partition including primary partition, extended partition, logical

Transferred from http://www.chenyajun.com/2009/03/06/2408 http://wiki.xensource.com/xenwiki/XenArchitecture?action=AttachFile&do=get&target=Xen+Architecture_Q1+ 2008.pdf A Xen virtualization environment consists of a set of projects that work

Special Note: 1, this article is only the face of database application development programmer, not suitable for professional DBA,DBA in the database performance optimization needs to know more knowledge; 2, many of the examples and concepts are

B-Tree 1. B-Tree definition A B-tree is a balanced, multi-channel lookup tree that is useful in file systems. Definition: An M-order B-tree, or an empty tree, or a M-fork tree that satisfies the following attributes:At most, there are M Shang

First, unreasonable index design ----Example: The table record has 620000 rows, and the following SQL runs under different indexes: ----1. A non-clustered index was built on date Select COUNT (*) from the record where date > ' 19991201 ' and date 20

first, unreasonable index design ----Example: The table record has 620000 rows, and the following SQL runs under different indexes: ----1. A non-clustered index was built on date Select COUNT (*) from the record where date > ' 19991201 ' and date 20

The original: Everyone is DBA (VII) B-Tree and + + TreeB-Tree (B-tree) is a balanced lookup tree designed for auxiliary access devices such as disk, which implements find, sequential read, insert, and delete operations with O (log n) time complexity

Learned a few good optimization methods:1. Technology optimizationThere are many ways to optimize SQL itself, such as indexing and ensuring the proper use of indexes, analysis of execution plan, in the context of cost-based execution scenario,