phantom orchestration

times, but the read structure is inconsistent. For example, in table A (name, age), record 1 is name = 'x', age = 188. The operation is as follows: Transaction 1 reads data for the first time in the structure of 'xinysu ', age = 188, and the result of the second read is name = 'xinysu', age = 288, when the records in the same row are read multiple times but the results are inconsistent, the transaction cannot be read repeatedly. 4.4 phantom readThe s

Document directory 2.2.1 concurrency consistency 2.2.2 solutions to concurrency consistency problems 2.2.3 transaction isolation level 2.2 SQL Server 2000 + ADO. Net concurrency control 2.2.1 concurrency consistency Common concurrency consistency problems include: Lost modifications, non-repeated reads, dirty reads, and Phantom reads (Phantom reads are often classified as non-repeated reads in some mat

of data and reading data that was not committed by the previous transaction, and if the previous transaction failed to roll back, the latter transaction read the error data, causing dirty reads. Ii. non-repeatable reads cannot be read repeatedlyA transaction reads the same data more than once, and when the transaction is not finished, the data was also manipulated by another transaction, and the data was updated by the second transaction between two times of the first transaction, so that the f

Delete from Test .... Add delete corresponding to the lock Commit When a transaction commits, the lock corresponding to the INSERT, update, and delete are released simultaneously While this approach does not prevent deadlocks, the two-phase lock protocol ensures that concurrent scheduling of transactions is serializable (serialization is important, especially in data recovery and backup). Second, the lock mode in the transaction 1. Four isolat

1. Database Transaction ACID Properties4 Features of database transactions:Atomicity (Atomic): operations in a transaction either succeed or fail;Consistency (consistency): After a transactional operation, the state of the database and the business rules are consistent; For example, the total amount of the account is not changed after mutual transfer;Isolation (Isolation): multiple transactions, like serial execution, do not affect each other;Persistence (Durability): After a transaction commits

1. Concurrency consistency Common concurrency consistency problems include: Lost modifications, non-repeated reads, dirty reads, and Phantom reads (Phantom reads are often classified as non-repeated reads in some materials ).1.1 lost Modification Next, let's take an example to illustrate the data inconsistency caused by concurrent operations. Consider an activity sequence in the aircraft booking system: A

Document directory 2.2.1 concurrency consistency 2.2.2 solutions to concurrency consistency problems 2.2.3 transaction isolation level 2.2 SQL Server 2000 + ADO. Net concurrency control 2.2.1 concurrency consistency Common concurrency consistency problems include: Lost modifications, non-repeated reads, dirty reads, and Phantom reads (Phantom reads are often classified as non-repeated reads in some mat

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Document directory 2.2.1 concurrency consistency 2.2.2 solutions to concurrency consistency problems 2.2.3 transaction isolation level From http://www.cnblogs.com/zhenyulu/articles/330494.html The complete code of this part can be downloaded from here.2.2 SQL Server 2000 + ADO. Net concurrency control 2.2.1 concurrency consistency Common concurrency consistency problems include: Lost modifications, non-repeated reads, dirty reads, and Phantom re

phantom reads one by one. The default isolation level set by MySql is Repeatable Read, which can be Repeatable Read. Isolation level can be configured. √: Possible Occurrence ×: no Dirty read Non-repeated read Phantom read Read uncommitted √ √ √ Read committed × √ √ Repeatable read × × √ Serializable × × × Not

2.2.1 Concurrency Consistency issuesCommon concurrency concurrency Consistency issues include: missing changes, non-repeatable reads, read dirty data, Phantom reads (Phantom reads are often associated with non-repeatable reads in some materials).2.2.1.1 Missing changesLet's take a look at an example that shows inconsistencies in the data caused by concurrent operations.Consider an activity sequence in the a

. Read committed-level read committed (also known as read committed content) can prevent dirty reads. This level of query reads only submitted data changes. If the transaction needs to read data modified by another unfinished transaction, the transaction will wait until the first transaction is completed (committed or rolled back ). Repeatable read: Lock all data used in the query to prevent other users from updating data. However, other users can insert new

transaction read the error data, which resulted in dirty reads.Ii. non-repeatable Reads non-repeatable readingA transaction reads the same data multiple times, and when the transaction is not finished, another transaction also operates on the data, and the second transaction updates the data between the first transaction two reads, and then the first transaction is read two times before the data is different, which results in non-repeatable reads.Iii. Phant