Understand MySQL8
Understand MySQL8
I have been using MySQL5 before, and recently encountered a new project, try to upgrade to 8 and see the scenery on the mountain.
New features
MySQL directly jumped from 5.7 to release 8.0. The official said that the changes are great, and the version number does not need to be progressive.
- The enhanced NoSQL is here as a document database (similar to MongoDB), you need to open the X plug-in before use (provide X protocol support, the supporting client is MySQL Shell and related connectors);
- Better indexing mechanism, adding hidden index and descending index ;
- The encryption mechanism defaults to sha2, which was originally sha1, because Google changed it after cracking sha1 ;
- Enhance InnoDB , including auto-increment, index, deadlock, shared lock, encryption, etc., and also support Atomic DDL;
- Added support transaction data dictionary 1 ;
- Modify the default character set to utf8mb4 .
Storage engine
| Engine | Support | Comment | Transactions | FAR | Savepoints |
|---|---|---|---|---|---|
| InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
| BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO |
| MyISAM | YES | MyISAM storage engine | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| ARCHIVE | YES | Archive storage engine | NO | NO | NO |
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL |
Compare the storage engine of MariaDB next door :
| Engine | Support | Comment | Transactions | FAR | Savepoints |
|---|---|---|---|---|---|
| MRG_MyISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| CSV | YES | Stores tables as CSV files | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
| MyISAM | YES | Non-transactional engine with good performance and small data footprint | NO | NO | NO |
| SEQUENCE | YES | Generated tables filled with sequential values | YES | NO | YES |
| Aria | YES | Crash-safe tables with MyISAM heritage | NO | NO | NO |
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| InnoDB | DEFAULT | Percona-XtraDB, Supports transactions, row-level locking, foreign keys and encryption for tables | YES | YES | YES |
The new version of MySQL8 has less sequence than mariadb, but more archive and Blackhole.
index
To be added. . .