mongodb acid

Tags: delete repeatable NSIs database system ora complete serialization differentiation errorThis article tells the four characteristics (ACID) of transactions in the database, and will explain the isolation level of the transaction in detail. If a database claims to support transactional operations, then the database must have the following four features: ⑴ atomicity (atomicity) Atomicity means that all operations contained in a transaction are eithe

://blog.sina.com.cn/s/blog_3fc85e260100msz3.html Each transaction allows the database to be atomically transferred from a consistent permanent state to a new consistent permanent state, which can be said, the acid of the transaction (the transactional properties of atomicity, consistency, isolation and durability) property is the soul of a database transaction: · Atomic Nature The atomicity of a transaction is first reflected in the modification of

I. TransactionsDefinition: The so-called transaction, which is a sequence of operations that are either executed or not executed, is an inseparable unit of work.Preparation: In order to illustrate the acid principle of the transaction, we use bank accounts and money management cases for analysis.[SQL]View PlainCopyprint? Create a database Create Table account ( Idint Primary key not null, Namevarchar (40), Moneydouble ); There ar

Tags: io ar using SP strong data on art issuesThe following is from the third edition of High-performance MySQL, where understanding the acid of transactions and the four isolation levels helps us better understand the workings of the transaction.Here is a classic example of a banking application that explains the necessity of a transaction. If a bank's database has two tables: the cheque list (checking) and the savings Table (savings). Now to transfe

Label:First, the distributed domain cap theory The cap theorem refers to the three attributes of consistency (consistent), availability (availability), reliability (partition tolerance partition tolerance) when designing a distributed system, which is also known as the Brewer's theorem. The cap theorem clarifies the limitations of the system that can be implemented by a distributed system, and many distributed systems in the Internet are designed based on the primary satisfaction of usability an

there are two transactions that run at the same time and perform the same function, the isolation of the transaction will ensure that every transaction in the system considers only that the transaction is in use by the system. This attribute is sometimes called serialization, and in order to prevent confusion between transactional operations, the request must be serialized or sequenced so that only one request is used for the same data at a time. DurabilityAfter the transaction is completed, th

beijing–,cars_shanghai++, represented by 2 SQL statements: Update car set cars_beijing=cars_beijing-1 where id = 1; Update car set cars_shanghai=cars_shanghai-1 where id = 1; Now use this example to understand acid,1. atomicity (atomicity), which means that this transaction either does not execute, or executes all, is the above 2 statements, not allowed to execute only one without executing the second day statement.2. Consistency (consistency), wh

Database transactions must have acid properties, and acid is an abbreviation for atomic (atomicity), consistency (consistency), isolation (isolation), and durability (persistence). Atomicity: The entire database transaction is an indivisible unit of work. The entire transaction succeeds only if all operations in the library are executed successfully, and if any SQL statement in the transaction fails, then

CAP, acid for in-depth understanding of the distributed environment in the design of technical options have important guidance role, so here to do the next finishing. 1. Cap principle 1.1 Definitions The CAP is a short name for "consistency,avalilability, Partition tolerance", the contents of which are: (1) Strong consistency : In the case of multiple copies of the same data in a distributed system, the effect of updating the data is the same as that

About the acid of the databaseTransferred from: http://blog.csdn.net/shuaihj/article/details/14163713I. TransactionsDefinition: The so-called transaction, which is a sequence of operations that are either executed or not executed, is an inseparable unit of work.Preparation: In order to illustrate the acid principle of the transaction, we use bank accounts and money management cases for analysis.// 创建数据库 cr

transaction cannot see the data in the middle of a time when other transactions are running.DurabilityAfter the transaction is completed, the changes made to the database by the firm persist in the database and are not rolled back.Because an operation typically contains many sub-operations that can cause problems with hardware corruption or other factors, it is not easy to implement acid correctly. The acid