index mysql

1, installation Coreseek1.1 First upgrade or install system dependent libraries　　　　Yum install make gcc g++ automake libtool mysql-client libmysqlclient15-dev libxml2-dev Libexpat1-dev　　1.2 Downloads Coreseek3.2.14Decompression: Tar zxvf coreseek-3.2

1, the data type is implicitly converted with the view whether the index is used2,select_typeSelect Type, which has the following values2.1 Simple It represents a straightforward select with no union and subquery2.2 Primary The outermost select, in

Write in front: indexes have a critical impact on the speed of queries, and understanding indexes is also a starting point for database Performance tuning. Consider the following scenario, assuming that a table in the database has 10^6 records, the

Note: This article is reproduced from http://www.hollischuang.com/archives/914In computer science, a lock is a synchronization mechanism used to forcibly restrict access to resources when executing multiple threads, which is used to guarantee the

explain SyntaxEXPLAIN SELECT ... Variant: 1. EXPLAIN EXTENDED SELECT ... "Decompile" The execution plan into a SELECT statement, run show WARNINGS to get the query statement 2 optimized by the MySQL optimizer. EXPLAIN Partitions SELECT ... Explain

Write in front: indexes have a critical impact on the speed of queries, and understanding indexes is also a starting point for database Performance tuning. Consider the following scenario, assuming that a table in the database has 10^6 records, the

MySQL table operations 1,//create tables mysql>create table usertest (id int () PRIMARY key NOT NULL Auto_increment,url varchar (a) not null); 2 Change table name mysql>alter  table usertest Rename to Cmf_usertest;mysql>alter table zm_useroplog  day 

MySQL Execution plan interpretationexplain SyntaxEXPLAIN SELECT ... Variant:SelectSelect ... Explain for partitioned tables Information contained in the execution planIDContains a set of numbers that indicate the order in which a SELECT clause

Databases are the foundation of most web application development. If you are using PHP, then most of the database with MySQL is also an important part of the lamp architecture. PHP looks simple, and a beginner can start writing functions in a few

explain SyntaxEXPLAIN SELECT ... Variant: 1. EXPLAIN EXTENDED SELECT ... "Decompile" The execution plan into a SELECT statement, run show WARNINGS to get the query statement 2 optimized by the MySQL optimizer. EXPLAIN Partitions SELECT ... Explain

Original: http://www.jb51.net/article/74564.htmFirst, connect the databaseFormat: mysql-h host address-u user name-P user Password1.1. Connect to MySQL on this computer.First open the DOS window, then enter the directory Mysql\bin, and then type the

Background knowledge:MySQL has three levels of Lock: page level, table level, row level.The MyISAM and memory storage engines use table-level locks (table-level locking), BDB storage engines use page locks (page-level locking), but table-level locks

Excerpt from: http://www.jb51.net/article/33736.htmWith the help of explain, you know when to add an index to the table to use the index to find records and make the select run faster.If some problems arise due to improper use of the index, you can

Mysql InnoDB Line Lock Implementation method innodb row locks are implemented by locking the index entries on the index, which is different from Oracle, which is achieved by locking the corresponding data rows in the data block. InnoDB This type of

EXPLAIN is the main way to see how the MySQL optimizer decides to execute a query, a feature that has limitations, that it will always tell the truth, but that it can get the best information. Learn to explain EXPLAIN, and you'll understand how the

Original address: http://blog.itpub.net/29254281/viewspace-1398273/ MySQL chooses what to think before you can read the isolation level repeatedly. Gap Lock MySQL before use There are three must be aware of: (with the depth of understanding

1. Index Use principle1), the leftmost prefix matching principle, MySQL will always match to the right until it encounters a range query (>, 3 and D = 4 If the order is established (A,B,C,D) Index, D is not indexed, if the establishment (A,B,D,C)

MySQL deadlock problem related knowledge is the main content of this article, we will introduce this part of the content, we hope to be able to help you.1. The lock mechanism of MySQL common storage engineMyISAM and memory with table-level lock

MySQL Dual master ConfigurationPrepare the environment: the server operating system is RHEL6.4 x86_64 To minimize the installation. Both host A and host B shut down the firewall and SELINUX with IP addresses of 192.168.131.129 and

Rotor http://www.linuxidc.com/Linux/2015-06/119354.htmDirectoryPreparatory workOperating EnvironmentConfirm your version of the installationDownload MySQLInstall MySQLPreparing the installation EnvironmentCompiling and installingConfigure