MySQL Storage engine

What is a storage engine

The storage engine is how to store the data, how to index the stored data, and how to update and query the data. Because the storage of data in a relational database is stored as a table, the storage engine can also be called a table type

There is only one storage engine in a database such as Oracle and SQL Server, and all data storage management mechanisms are the same. The MySQL database provides a variety of storage engines. Users can choose different storage engines for the data table according to different requirements, and users can write their own storage engine according to their own needs.

Two MySQL-supported storage engines

Mysql> Show Engines\g #查看数据库的所有引擎

Mysql> Show variables like ' storage_engine% ' #查看当前数据库正在使用的存储引擎

the #InnoDB storage engine supports transactions and is designed primarily for online transaction processing (OLTP) applications. It features a row lock design, supports foreign keys, and supports non-locking reads like Oracle, where the default read operation does not generate locks. From MySQL5.5.8The version starts as the default storage engine. The InnoDB storage engine places the data in a logical table space, which is managed by the InnoDB storage engine itself like a black box. From MySQL4.1(including4.1version, you can store the table for each InnoDB storage engine in a separate IBD file. In addition, the InnoDB storage engine supports a bare device (rowDisk) is used to establish its table space. InnoDB achieves high concurrency by using multi-version concurrency control (MVCC), and implements the SQL standard4Isolation level, which defaults toRepeatablelevel, while using a type called NETX-KeyLocking strategies to avoid the creation of Phantom-reading (phantom) phenomena. In addition to this, the InnoDB storage engine also provides insert buffering (InsertBuffer), write two times (DoubleWrite), Adaptive Hash Index (adaptive hashIndex), read-ahead (Readahead) and other high-performance and highly available features. For storage of data in tables, the InnoDB storage engine uses aggregation (Clustered), each table is stored in the order of the primary key, and if you do not explicitly specify a primary key when the table is defined, the InnoDB storage engine generates one for each row6the ROWID of the byte and takes this as the primary key. The InnoDB storage engine is the most commonly used engine for MySQL databases, and successful applications from companies such as Facebook, Google, and Yahoo! have proven that the InnoDB storage engine is highly available, high performance, and highly scalable. The mastery and understanding of its underlying implementation also requires time and technology to accumulate. If you want to learn more about how the InnoDB storage engine works, implemented, and applied, you can refer to the "MySQL Insider: InnoDB Storage Engine" book. #MyISAM storage Engine does not support transactions, table lock design, full-text indexing, mainly for some OLAP database applications, in MySQL5.5.8before the version is the default storage engine (except for the Windows version). A big difference between a database system and a file system is the support for transactions, which are not supported by the MyISAM storage engine. It is not difficult to understand the fundamental. Does the user need to have a transaction in all applications? In the Data warehouse, if there is no ETL these operations, but simply through the report query also need transaction support? In addition, the MyISAM storage engine is unique in that its buffer pool caches only (cache) index files, Instead of caching data files, this is not the same as most databases. #NDB storage engine year, MySQL AB acquired the NDB storage engine from Sony Ericsson Corporation. The NDB storage engine is a clustered storage engine, similar to Oracle's RAC cluster, but unlike the share everything structure of the Oracle RAC, its structure is a cluster architecture that share nothing, thus providing a higher level of high availability. The NDB storage engine is characterized by the fact that the data is all in memory (from5.1Version, the non-indexed data can be placed on the disk), so the primary key lookup (Primary Keylookups) is extremely fast and can be added online with NDB data node to improve database performance linearly. Thus, the NDB storage engine is a highly available, high-performance, highly scalable database cluster system, which is also a database application type for OLTP. #Memory Storage engine as its name, the data in the memory storage engine is stored in RAM, the database restarts or crashes, and the data in the table disappears. It is ideal for staging tables that store temporary data in an OLTP database application or as a dimension table for the Data warehouse in an OLAP database application. The memory storage engine uses a hash index by default instead of the usual familiar B+Tree Index. #Infobright Storage Engine third-party storage engine. It is characterized by columns rather than rows, making it ideal for OLAP database applications. Its official website is http://www.infobright.org/, there are a number of successful data warehousing cases to be analyzed. #NTSE Storage Engine NetEase has developed a storage engine for its internal use. The current version does not support transactions, but provides features such as compression, row-level caching, and, in the near future, memory-oriented transaction support. #BLACKHOLE黑洞存储引擎 that can be applied to the distribution Master library in primary and standby replication. The MySQL database also has many other storage engines, which are just some of the most commonly used engines. If you like, you can write your own engine, this is the ability of open source to us, but also the charm of open source. 

Three. Using the storage engine

Method 1: Specify when the table is built

MariaDB [db1]> CREATE TABLE innodb_t1 (ID int,name char) engine=InnoDB;
MariaDB [db1]> CREATE TABLE innodb_t2 (id int) engine=InnoDB;
MariaDB [db1]> Show create TABLE innodb_t1;
MariaDB [db1]> Show create TABLE innodb_t2;

MySQL Storage engine