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Transaction --Transation
What business is?
Transaction refers to a set of operations on the logical set of operations either all succeed, or all fail.
Things features:
1. Atomic Atomic: A transaction is an indivisible unit of work, either all operations in a transaction happen or none happen.
2. Consistency Consistent: transactional integrity of the data before and after processing must be consistent.
3. Isolation Isolated: When a plurality of users concurrent access to the database, a user's transaction can not be firm interfere with other users, data between a plurality of concurrent transactions to be isolated from each other.
4. Persistence Durable: Once a transaction is committed, it changed data in the database is permanent, even if the database fails nor should it have any impact.
Spring transaction management interface:
PlatformTransactionManager: Transaction Manager
TransactionDefinition: transaction definition information (transaction isolation level, propagation behavior)
TransactionStatus: Transaction specific operational state
(. 1) REPEATABLE_READ, Mysql isolation level defaults
(2) READ_COMMITTED using the Oracle default isolation level
If you do not consider isolation, it will lead to the following security issues:
1. dirty read . One transaction reads another transaction but not yet submitted to rewrite data, if the data is rolled back, the read data is invalid.
2. A non-repeatable read . In the same transaction, the result of multiple reads of the same data returned is different.
3. The phantom read . After a transaction reads a few rows, a second transaction inserts some records, phantom read occurs. Later query, the first transaction would not have found that some of the original recording.
