ACID Properties
I am a Tech Enthusiast having 13+ years of experience in 𝐈𝐓 as a 𝐂𝐨𝐧𝐬𝐮𝐥𝐭𝐚𝐧𝐭, 𝐂𝐨𝐫𝐩𝐨𝐫𝐚𝐭𝐞 𝐓𝐫𝐚𝐢𝐧𝐞𝐫, 𝐌𝐞𝐧𝐭𝐨𝐫, with 12+ years in training and mentoring in 𝐒𝐨𝐟𝐭𝐰𝐚𝐫𝐞 𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫𝐢𝐧𝐠, 𝐃𝐚𝐭𝐚 𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫𝐢𝐧𝐠, 𝐓𝐞𝐬𝐭 𝐀𝐮𝐭𝐨𝐦𝐚𝐭𝐢𝐨𝐧 𝐚𝐧𝐝 𝐃𝐚𝐭𝐚 𝐒𝐜𝐢𝐞𝐧𝐜𝐞. I have 𝒕𝒓𝒂𝒊𝒏𝒆𝒅 𝒎𝒐𝒓𝒆 𝒕𝒉𝒂𝒏 10,000+ 𝑰𝑻 𝑷𝒓𝒐𝒇𝒆𝒔𝒔𝒊𝒐𝒏𝒂𝒍𝒔 and 𝒄𝒐𝒏𝒅𝒖𝒄𝒕𝒆𝒅 𝒎𝒐𝒓𝒆 𝒕𝒉𝒂𝒏 500+ 𝒕𝒓𝒂𝒊𝒏𝒊𝒏𝒈 𝒔𝒆𝒔𝒔𝒊𝒐𝒏𝒔 in the areas of 𝐒𝐨𝐟𝐭𝐰𝐚𝐫𝐞 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐦𝐞𝐧𝐭, 𝐃𝐚𝐭𝐚 𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫𝐢𝐧𝐠, 𝐂𝐥𝐨𝐮𝐝, 𝐃𝐚𝐭𝐚 𝐀𝐧𝐚𝐥𝐲𝐬𝐢𝐬, 𝐃𝐚𝐭𝐚 𝐕𝐢𝐬𝐮𝐚𝐥𝐢𝐳𝐚𝐭𝐢𝐨𝐧𝐬, 𝐀𝐫𝐭𝐢𝐟𝐢𝐜𝐢𝐚𝐥 𝐈𝐧𝐭𝐞𝐥𝐥𝐢𝐠𝐞𝐧𝐜𝐞 𝐚𝐧𝐝 𝐌𝐚𝐜𝐡𝐢𝐧𝐞 𝐋𝐞𝐚𝐫𝐧𝐢𝐧𝐠. I am interested in 𝐰𝐫𝐢𝐭𝐢𝐧𝐠 𝐛𝐥𝐨𝐠𝐬, 𝐬𝐡𝐚𝐫𝐢𝐧𝐠 𝐭𝐞𝐜𝐡𝐧𝐢𝐜𝐚𝐥 𝐤𝐧𝐨𝐰𝐥𝐞𝐝𝐠𝐞, 𝐬𝐨𝐥𝐯𝐢𝐧𝐠 𝐭𝐞𝐜𝐡𝐧𝐢𝐜𝐚𝐥 𝐢𝐬𝐬𝐮𝐞𝐬, 𝐫𝐞𝐚𝐝𝐢𝐧𝐠 𝐚𝐧𝐝 𝐥𝐞𝐚𝐫𝐧𝐢𝐧𝐠 new subjects.
RDBMS works under 4 properties (ACID)
Atomicity
If any operation is performed on the data, either the entire transaction should be executed or should not be executed at all.
Single unit of work = Multiple queries.
For example, in an application that transfers funds from one account to another, the atomicity property ensures that, if a debit is made successfully from one account, the corresponding credit is made to the other account.
- In the above diagram, it can be seen that after crediting $10, the amount is still $100 in account B. So, it is not an atomic transaction.
Consistency
Data is in a consistent state when a transaction starts and when it ends.
For example, in an application that transfers funds from one account to another, the consistency property ensures that the total value of funds in both the accounts is the same at the start and end of each transaction.
Isolation
Isolation means that any data being used during the processing of one transaction cannot be used by another transaction until the first transaction is complete.
For example, if two people deposit $100 into another account with a balance of $900, the first transaction must add $100 to $900, and the second must add $100 to $1000. If the second transaction reads the $900 before the first transaction has completed, both transactions will seem to succeed, but $100 will have gone missing. The second transaction must wait until it alone is accessing the data.
Durability
Durability refers to the fact that once data from a transaction has been committed, its effects will remain, even after a system failure.
While a transaction is under way, the effects are not persistent. If the database crashes, backups will always restore it to a consistent state prior to the transaction commencing. Nothing a transaction does should be able to change this fact.
For example, in an application that transfers funds from one account to another, the durability property ensures that the changes made to each account will not be reversed.
