Encyclopedia > Write-Read conflict

  Article Content

Write-Read conflict

In computer science, in the field of databases, Write-Read Conflict, also known as reading uncommitted data, is a computational anomaly associated with interleaved execution of transactions.

Given a schedule D

<math>D = \begin{bmatrix}
T1 & T2 \\ R(A) & \\ W(A) & \\
 & R(A) \\
 & W(A)\\
 & R(B) \\
 & W(B) \\
 & Com. \\
R(B) & \\ W(B) & \\ Com. & \end{bmatrix}</math>

T2 could read a database object A, modified by T1 which hasn't committed. This is a dirty read.

T1 may write some value into A which makes the database inconsistent. It is possible that interleaved execution can expose this inconsistency and lead to inconsistent final database state, violating ACID rules.

Strict 2PL, overcomes this inconsistency by locking T2 out from A. Unfortunately, deadlocks is something Strict 2PL does not overcome as well.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Wheatley Heights, New York

... 18 to 24, 29.9% from 25 to 44, 23.8% from 45 to 64, and 7.9% who are 65 years of age or older. The median age is 35 years. For every 100 females there are 95.1 males. ...

 
 
 
This page was created in 24.8 ms