devialet phantom

, the physical log records the details of the modified page, and the logical log records the action statement. Physical log recovery is faster than logical logs. 2. How transactions are implementedThe role of a transaction: A transaction transforms a database from a consistent state into another consistent state.The mechanism of a transaction is generally summarized as the "ACID" principle i.e. atomicity (A), consistency (C), Isolation (I), and Persistence (D). Atomicity: All ope

Intent table lock:before adding a lock, you should first add a table-level intent Lock:Intent Shared Lock (IS): indicates that a transaction is ready to join a shared lock on a data row, which means that a data row is locked before a shared lock must be obtained for that table. Intent Exclusive Lock (IX): Similar to the above, the transaction is prepared to add an exclusive lock to the data row, stating that the transaction must obtain an IX lock on the table before a data row is added to the e

created:soft 0Just created:soft 1Just created:soft 2Just created:soft 3Just created:soft 4Just created:soft 5Ju St Created:soft 6Just created:soft 7Just created:soft 8Just created:soft 9Just created:weak 0Just created:weak 1Just Created:weak 2Just created:weak 3Just created:weak 4Just created:weak 5Just created:weak 6Just created:weak 7Just C Reated:weak 8Just created:weak 9Finalizing ... Weak 7Finalizing ... Weak 8Finalizing ... Weak 9Finalizing ... Weak 4Finalizing ... Weak 5Finalizing ... W

between transactions, with four isolation levels. First you need to explain a few conceptual definitions related to isolation: (1) Dirty reading: Refers to the transaction read dirty data, the so-called dirty data, refers to the incorrect data, such as the transaction during the execution of the modification of a record, and then rollback, if the other transaction read the record in the middle of the modified value, dirty read. (2) Non-repeatable reads: A transaction reads the same existing rec

-repeatable read (nonrepeatable Read): When a transaction reads the data it has read before, the discovery data has been modified or deleted by other committed transactions.there is no read (Phantom Read): short for "phantom read". When a transaction is re-queried by a previous condition, the returned result set contains new data that satisfies the conditions that were inserted by other committed transactio

ReviewOf the many storage engines in MySQL, only InnoDB supports transactions, and all of the transaction isolation levels described here refer to the transaction isolation level under InnoDB.READ UNCOMMITTED: One transaction can read uncommitted modifications to another transaction. This can lead to dirty reading, phantom reading, non-repeatable reading problems. (Basic useless)Read committed: One transaction can read only the modifications that have

two query process to update the original data, so the same select might return different results.Repeatable Read (can be reread)This is the default transaction isolation level for MySQL, which ensures that multiple instances of the same transaction will see the same rows of data while concurrently reading the data. In theory, however, this can lead to another tricky problem: Phantom Reading (Phantom read).

levels (snapshot of the read-committed isolation level based on the row version).Different isolation levels to control dirty read, non-repeatable read, Phantom Reading has a certain degree of control, also can have a certain extent of influence,The lower the isolation level, the higher the concurrency, but the more likely it is to produce dirty reads, non-repeatable reads, and Phantom reads; With the submi

solve the database transaction concurrency problem. Copyright Notice and Acknowledgements: This article original nerd RicoAuthor Blog address: http://blog.csdn.net/justloveyou_/ Examples of the explanations for dirty reads, non-repeatable reads, and Phantom reads are from the blog post, "Database transaction isolation level."I. Overview of transactionsIn general, each request of a user corresponds to a business logic method, and each business logic m

transfer money to the card before A's withdrawal. 4. Durability: after the transaction is completed, all updates to the database by the transaction will be saved to the database and cannot be rolled back. Conclusion: Atomicity is the foundation of transaction isolation, isolation and persistence are the means, and the ultimate goal is to maintain data consistency. Ii. Transaction concurrency 1. Dirty read: Transaction A reads the data updated by transaction B, and then B rolls back, then the da