【知识库】--mysql engines MyISAM vs InnoDB(146)

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MyISAM vs InnoDB
MyISAM:不支持事务，不支持行级锁；
支持 fullindex indexing ；
最多 64 keys per table;
不支持外键；
支持table level locking;
three files: formate file （store table structure）, data file store rows,index file store indexes;【table.frm,table.MYD,table.MYI】
支持：读写锁模式；readWriteLock model
InnoDB：
支持事务；COMMIT ROOLBACK SAVEPOINT
支持行级锁；
Data and indexes stored in one “tablesapce” file;
undo space: insert undo space, update undo space;
Only file in database directity is .frm;
tablesapce limited to 64 terabytes（TB）;
Use variable length strings whenever appropriate;
Many system variables for tuning performance;

Insert buffer (change buffer)
buffers changes to secondary indexes and avoids substantial random IO that would be required to read-in-secondary index pages from disk.

小技巧
1 mysql 展示存储引擎 show engines \G;
2 mysql 换行 system clear；
3 展示表状态： show table status like ‘City’ \G

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