phantom playbooks

Lost modifications, non-repeated reads, dirty reads, Phantom readsCommon 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 ).Loss of ModificationNext, let's take an example to illustrate the data inconsistency caused by concur

transactionOptions2 = new TransactionOptions {IsolationLevel = IsolationLevel. ReadCommitted };Using (var ts1 = new TransactionScope (transactionscospontion. Required, transactionOptions1 )){// PrerequisitesUsing (var context = new TestEntities ()){Assert. AreEqual ("Li yunniu", context. Tables. First (). Name );}ThreadPool. QueueUserWorkItem (data =>{Using (var ts2 = new TransactionScope (transactionscospontion. Required, transactionOptions2 )){// Modify dataUsing (var context = new TestEntiti

Phantom of the Opera I wanted to write a sense of listening, and I was ashamed to say that I did not dare to speak out after reading a few comments from Iyin. I haven't even figured out what brand little looks like even a B. While reading subtitles, watching the role dress with a telescopeTo tell the truth, subtitles are really not very well matched. Obviously, there is only one short line on the subtitles. Listening to the smooth London cavity of

};Var transactionOptions2 = new TransactionOptions {IsolationLevel = IsolationLevel. ReadCommitted }; Using (var ts1 = new TransactionScope (transactionscospontion. Required, transactionOptions1 )){// PrerequisitesUsing (var context = new TestEntities ()){Assert. AreEqual ("Li yunniu", context. Tables. First (). Name );} ThreadPool. QueueUserWorkItem (data =>{Using (var ts2 = new TransactionScope (transactionscospontion. Required, transactionOptions2 )){// Modify dataUsing (var context = new Te

Dirty read (dirty read) unrepeatable read (phantom problem) Parsing1. Dirty read First, distinguish between dirty pages and dirty data Dirty pages are modified pages in the memory buffer pool. They are not flushed to the hard disk in time, but are already written to the redo log. It is normal to read and modify the page of the buffer pool, which can improve efficiency and synchronize with flush. Dirty data indicates that the transaction has modified t

file is infected, causing more risk to the user. "Agent Trojan" variant Aaxa will be registered as a system service in the infected computer, so as to achieve the power-on self-starter. English Name: EXPLOIT.SQLSHELL.O Chinese name: "SQL Phantom" variant O Virus Length: 227328 bytes Virus type: Vulnerability virus Hazard Level: ★ Impact Platform: Win 9x/me/nt/2000/xp/2003 MD5 Check: 750e784163ea09d7889b4e1110b985e2 Feature Description: EXPLO

, and commit the transaction so that the update of transaction a overwrites the update of transaction B.5) Phantom reading: a phenomenon that occurs when a transaction is not executed independently, such as when the first transaction modifies data in a table, which involves all rows of data in the table. At the same time, the second transaction modifies the data in the table by inserting a new row of data into the table. Then the user who will be work

broken, we only have to fall down and become a sheep that has been arbitrarily slaughtered and trampled. Talent is the backbone of Zhongguancun, the backbone of China's electronics industry, and even the backbone of our national rejuvenation. We need talent, and we need that one! We need talent, but in fact our small Talent Team is shrinking. Another batch of scientific research projects were forced to shelve because there were no "talents". The IBM on xuanyuan was delayed, and Microsoft on Kyu

Http://my.oschina.net/u/219582/blog/59834] 1.Dirty read: Dirty read means that when a transaction is accessing data and modifying the data has not been committed to the database, another transaction also accesses the data, then the data is used. 2. non-repeated read : reads the same data multiple times in a transaction. When the transaction is not completed, another transaction also accesses the same data. Therefore, the data read twice in the first transaction may be different because of

1. Some problematic reads in the transaction: dirty read, non-repeatable read, Phantom readThe dirty read (Dirty Read) transaction T1 updated the contents of a row of records, but did not commit the changes. The transaction T2 reads the updated row, and then T1 performs the rollback operation, canceling the modification that was just made. Now the line read by T2 is invalid.The non-repeatable read (nonrepeatable Read) transaction T1 reads a row of rec

1. Dirty read: Dirty read means that when a transaction is accessing data and modifying the data has not been committed to the database, another transaction also accesses the data, then the data is used. 2. Repeated read is not allowed.: Refers to reading the same data multiple times in a transaction. When the transaction is not completed, another transaction also accesses the same data. Therefore, the data read twice in the first transaction may be different because of the modification of the s

Database dirty reads, non-repeated reads, and Phantom reads are all related to the isolation of transactions. First, let's take a look at the four features of transactions.Four major features of transactions (ACID ): Atomicity: a transaction is the logical unit of work of the database. It either executes all the modifications to the database or does not execute all the modifications. Consistemcy: before and after a transaction, the database status

To take the above, the benefits of using structs instead of class are outlined, and using class will make our programs "accidental sharing" and "circular referencing" dangerous, and the reliance on class in traditional object-oriented development comes mainly from our reliance on "inheritance". Swift2.0 introduced protocol extensions, the previous "class-Inherit" functionality can be implemented using the "struct (enum)-Protocol-Protocol extension", and is more efficient and flexible. Back to th

simply talk about references ( excerpt from Java Virtual Machine Second Edition )Attribution: Wanderone or four types of references　　After JDK 1.2, Java extends the concept of references into strong references (strong Reference), soft references (Soft Reference), weak references (Weak Reference), virtual references (Phantom Reference) 4 species, these 4 kinds of reference strength gradually weakened.Ii. Introduction and timing of recycling1. Strong ci

Small weave today brings "the Charm Family Router Speed Edition remote switch computer tutorial" ~ 1. To the computer BIOS to make the necessary settings (need network card, motherboard support remote wake-up); 2. The computer must be connected to the Phantom router via a network cable (not wireless). Meet the above two conditions can be looked down! Here are a few steps to implement a remote computer wakeup and shutdown: remote computer wake-up

The Phantom Blue e mobile phone has several screen-cutting methods The Phantom Blue e mobile phone only a screenshot of the way, is "power button" and "Volume down the key", but it is worth noting that the charm of the blue-e mobile phone keypad length Oh, click the interception of the current screen, if the long press can be cut long screen oh, specific we will introduce. Explain the charm Blue E scree

One, dirty reading, non-repeatable reading, Phantom reading 1, dirty read: Dirty read refers to when a transaction is accessing the data, and the data has been modified, and this modification has not been committed to the database, then another transaction also accesses the data, and then used this data.For example:Zhang San's salary was 5000 and transaction a changed his salary to 8000, but transaction a was not yet submitted.MeanwhileTransaction B