Concurrent operation has big implications for data integrity. In order to guarantee integrity, a relational database system must comply with the ACID principle. This is normally implemented through transactions.
In ACID, A stands for Atomicity, and that means when data is modified by some transaction, either all of its data modifications are performed or none of them are performed.
The C in ACID stands for Consistency. When a data modification transaction completes, all data must be in a consistent state. All constraints must be satisfied, and all internal structures must be correct.
I is all about Isolation. Modifications made by one transaction must be isolated from those made by other concurrent transactions. This also implies that if you redo the same operations with the same starting data, the results will always be the same.
The D in ACID stands for Durability. When a transaction is complete the results are stored permanently in the system and persist even if a system failure occurs. Now in order to get you set up, so that you can follow along with all the demos, let me introduce you to the tools I’ll be using.
Cheers!
