SQL Server - Acid Properties (Atomicity, Consistency, Isolation, Durability) Example
Atomicity
It is one unit of work and does not dependent on previous and following transactions. This transaction is either fully
completed or not begun at all. Any updates in the system during transaction
will complete entirely. If
any reason an error occurs and the transaction is unable to complete all of its
steps, then the system will returned to the state where transaction was started
Consistency
Data is either committed or roll back, not “in-between” case where something has been
updated and something hasn’t and it will never leave your database
till transaction finished. If the transaction completes successfully, then all
changes to the system will have been properly made, and the system will be in a
valid state. If any error occurs in a transaction, then any changes already
made will be automatically rolled back. This will return the system to its
state before the transaction was started. Since the system was in a consistent
state when the transaction was started, it will once again be in a consistent
state.
Isolation
No transaction sees the intermediate results of
the current transaction. We
have two transactions both are performing the same function and running at the
same time, the isolation will ensure that each transaction separate from other until
both are finished.
Durability
Once transaction completed whatever the changes
made to the system will be permanent even if the system crashes right after
Whenever
transaction will start each will obey all the acid properties.
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