What is ACID

Answered by Jey on 2005-05-08 17:27:45: ACID is releated to transactions. It is an acronyam of Atomic, Consistent, Isolation and Durable. Transaction must following the above four properties to be a better one 
 
Atomic: It means a transaction must execute all or nothing at all. 
Consistent: Consistency is a transactional characteristic that must be enforced by both the transactional system and the application developer 
Isolation: Transaation must be allowed to run itselft without the interference of the other process or transactions. 
Durable: Durablity means that all the data changes that made by the transaction must be written in some type of physical storage before the transaction is successfully completed. This ensures that transacitons are not lost even if the system crashes.

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Jey

  • May 8th, 2005
 

ACID is releated to transactions. It is an acronyam of Atomic, Consistent, Isolation and Durable. Transaction must following the above four properties to be a better one 
 
Atomic: It means a transaction must execute all or nothing at all. 
Consistent: Consistency is a transactional characteristic that must be enforced by both the transactional system and the application developer 
Isolation: Transaation must be allowed to run itselft without the interference of the other process or transactions. 
Durable: Durablity means that all the data changes that made by the transaction must be written in some type of physical storage before the transaction is successfully completed. This ensures that transacitons are not lost even if the system crashes.

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Ritesh patni

  • Jul 25th, 2005
 

Atomic-- should execute all or nothing...rollback come into picture 
Consistent--Consistency is a transactional characteristic that must be enforced by both the transactional system and the application developer  
Isolation -- transaction must be allowed to run without interfering to the other transaction 
Durable -- all the update should be properly put into the database 
 
 

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A - Atomocity
C - Consistency
I - Isolation
D - Durability.

When Transactoon(Tx) middleware service is enabled on the Businesslogic the data on the application available outside or in DB s/w will give support for ACID properties.

Atomocity: The process of combining individual operation of a task in to single unit  is called  atomocity. The individual operations r those  operaion which we can not divide furtherly.

Consistency: When some rules are assign on apps data or DB data eventhough these rules are violated during  the execution of operations placed in a Tx  if there is a guarntee that no rules will be  violated at the end of the Tx (when Tx is comitted or rollback) we can say Tx is doing consistently well.

For more  clear for  Ex:  In the A/C table of  DB s/w balance column is there, rule applied on the balance column is you should not contain negative values, there is a TX having 20 operation is dealing with these data (balance column value) during the execution of these 20 operation, even though balance column become negative at the end of the Tx if balance column remains with positive value then we can say Tx is doing consistently well.

Isolation: When multiple users or application access DB data concurrently or simultaneously there is a posibility of data coruption.  The process of preventing these concurrent & interliving operation by applying locks on the DB at various levels is called Working with Isolation property.

Durability: When DB is crashed if there is a guarntee that we can bring DB back to original state without loosing any data is called support for Durability.  All DB s/w 's  are durability because of the log facilities they are giving.

Cheer..
ompraksh..

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