Transactions are a part of any database system. The core concept of a transaction is combining multiple steps to form a single operation. But let’s be clear: those steps are invisible to concurrently-occurring transactions. If a failure strikes and prevents a transaction from completion, none of the steps will have an effect on the database.
As a result, this type of transaction will be considered “atomic”, but they tend to either never happen or happen regularly.
Furthermore, when transactions are completed and accepted by a database, they become recorded on a permanent basis. As a result, if a crash occurs later, the transaction can’t be deleted. A transactional database makes sure updates made via transactions are stored permanently.
It’s important to remember that when several transactions take place at the same time in a database, none of them can see changes implemented by others if they’re incomplete. Updates that are undertaken by open transactions stay invisible to different transactions until they have been completed.
Beyond this, any updates will become visible at the same time. With PostgreSQL, every SQL transaction is treated as being run inside transactions. This means when you fail to issue a “begin” command, this command applies to each statement, as does the “commit” command.
A group of statements with these commands applied to them make up a transaction block. The “begin” command begins the transaction block and all statements will come after it. These form one transaction until a “commit” command brings it to a close.