Blockchain Transaction Life-cycle

Blockchain?technology is mostly about the transactions that we make digitally for ourselves. Eventually, these transactions make their way to the various blocks that become part of the Blockchain later on. So, it is important to understand the?transaction life cycle in Blockchain technology.

This lifecycle follows the journey of a single transaction as it makes its way through each stage in the process of joining the blockchain. Transaction in simple words is the process of sending money by the sender and the receiver receiving it. The Blockchain transaction is also quite similar, but it is made digitally.

Let us understand the various stages in a blockchain transaction life cycle with the help of an example.

Sourav and Suraj are two?Bitcoin?users. Sourav wants to send 1 bitcoin to Suraj.

1. First, Sourav gets Suraj’s wallet address (a wallet in the blockchain is a digital wallet that allows users to manage their transactions). Using this information, he creates a new transaction for 1 bitcoins from his wallet and includes a transaction fee of 0.003 bitcoin.
2. Next, he verifies the information and sends the transaction. Each transaction that is initiated is signed by a digital signature of the sender that is basically the private key of the sender. This is done in order to make the transaction more secure and to prevent any fraud.
3. Sourav’s wallet then starts the transaction signing algorithm which signs his transaction using his private key.
4. The transaction is now broadcasted to the memory pool within the network.
5. This transaction is eventually accepted by the miners. These miners, group this transaction into a block, find the?Proof of Work, and assign this block a?hash value?to be mapped into the blockchain.
6. This block is now placed on the Blockchain.
7. As this block gains confirmation, it is accepted as a valid transaction in the network.
8. Once this transaction is accepted, Suraj finally gets his bitcoin.

Levels of Locking in DBMS

The locking in a database can be done at 4 levels, which start with the database at the highest level and down via table and page to the row at the lowest level.

• Database Level
• Table Level
• Page-Level
• Row Level

Before we discuss the levels of locking, we should know about the types of locks or lock mode. So, there are 5 locks types in the locking and these are discussed below :

• Exclusive (X) Lock-??
• This method of locking differentiates the locks based on their usage. This also ensures that the data or information of a page will be reserved exclusively for those transactions that used the exclusive lock. These locks are applied on those resources only where a WRITE operation is performed. These locks can be applied to a page only if there is no other shared or exclusive type of lock is applied already.
• ?
• Shared (S) Lock –?
• This method of locking is applied only to the read operations. If this lock is applied to any row or a page, then it will reserve that row or page for the read operation. We can apply more than one lock on the same row or the same page, but it should not apply to any other type of lock.

• Intent exclusive (IX) Lock –?
• This method of locking explicit locking at a lower level with exclusive or shared locks. This means that if a transaction has used this type of lock, then it must be a case of modifying the lower level of resources by imposing exclusive lock separately.

• Intent shared (IS) Lock –?
• This method of locking is explicit locking at a lower level of the tree but only with shared locks. This means that if a transaction has used this type of lock, then it must be a case of reading the lower level of resources by imposing shared lock separately.
• ?
• Shared intent exclusive (SIX) Lock –?
• This method of locking states that the transaction is used to read the resources at a lower level. Here in SIX, we impose the shared lock on all the resources that are available at the lower level. The subtree rooted by that node is locked explicitly in shared mode and explicit locking is done at a lower level with exclusive mode locks. In this method, only one SIX can be acquired on a relation at a time and if there are any other transactions for updating any change, then it will block those transactions.

• Update (U) Lock –??
• This method of locking can be imposed on a record that already consists of a shared lock and if it has a shared lock already, then the update lock will impose another shared lock on the target row or page of relation. This is the same as an exclusive lock and also in some ways flexible. Here in this lock, after checking that the transaction holds the update lock for modifying the data, then the update lock will be modified into an exclusive lock.