MySQL storage engine

MySQL Storage engine for

Concept

Database storage engine is the bottom layer of database , Database management system uses data engine to create 、 Inquire about 、 Update and delete data

Different storage engines provide different storage mechanisms 、 Indexing mechanism , Locking mechanism .MySQL The core is the storage engine .

Users can choose different storage engines for data tables according to different requirements .

--  see MySQL All execution engines , The default engine is innoDB, Row level locking and foreign keys 
--  The way 1
show engines
--  The way 2
show variables like 'have%';

MySQL In support of 9 Storage engine , The default engine is InnoDB

Field parameter interpretation ：

Engine The parameter represents the name of the storage engine

Support parameter MySQL Whether the database management system supports the storage engine

Comment Parameters represent comments about the storage engine

Transactions Parameter indicates whether the storage engine supports transactions

XA Parameter indicates whether the distributed supported by the storage engine is consistent with XA standard

Savepoints Parameter indicates whether the storage engine supports savepoints in transaction processing

Operate the default engine

 --  Query the storage engine supported by the current database 
 show engines;
 
 --  View the current default storage engine 
 --  Mode one ：
  adopt `show engines`,Support Field is default Is the default engine 
 --  Mode two ：
 show variables like '%storage_engine%';
 
 --  View table engine (ENGINE= The following value is the current storage engine )
 show create table table_name;
 

 --  Specify the storage engine when creating a new table 
 create table (...) engine = MyISAM;

Modify the storage engine

modify MySQL The default storage engine of the database system ：

open my.ini The configuration file , find default-storage-engine = INNODB

Change to the name of the engine you want to change , Need to restart mysql The service will take effect .

Modify the database table storage engine

alter table table_name engine = INNODB;
alter table table_name engine = MyISAM;

Select storage engine

Each storage engine has its own characteristics 、 Advantages and application scenarios .

Common storage engine characteristics table

characteristic	MyISAM	InnoDB	MEMORY
Storage limits	Yes	64TB	Yes
Transaction security	I won't support it	Support	I won't support it
Locking mechanism	Table locks	Row lock	Table locks
B Tree index	Support	Support	Support
Hash index	I won't support it	I won't support it	Support
Full-text index	Support	I won't support it	I won't support it
Cluster index	I won't support it	Support	I won't support it
Data caching		Support	Support
The index buffer	Support	Support	Support
Data can be compressed	Support	I won't support it	I won't support it
Space use	low	high	N/A
Memory usage	low	high	secondary
Batch insertion speed	high	low	high
Support foreign keys	I won't support it	Support	I won't support it

• MyISAM, Because the engine does not support transactions , Foreign keys are also not supported , So the access speed is relatively fast , It is applicable to scenarios that do not require transaction integrity .
• InnoDB, Support transactions , Submit with , Rollback and crash recovery , Than MyISAM Take up more disk space
• MEMORY, The storage engine uses memory to store data , So this engine is fast , But there is no security ,【 It would have used redis Other memory types NOSQL Database replacement 】