Serializability is a type of property of DBMS in which each transaction is executed independently and automatically, even though these transactions are executed concurrently. In other words, we can say that if there are several transactions executed concurrently, then the main work of the serializability function is to arrange these several transactions in a sequential manner.
For better understanding, let's explain these with an example. Suppose there are two users ramu and ravi. Each executes two transactions. Let's transactions T1 and T2 are executed by ramu, and T3 and T4 are executed by ravi. Suppose transaction T1 reads and writes the data item A, transaction T2 reads the data item B, transaction T3 reads and writes the data item C and transaction T4 reads the data item D. Lets the schedule the above transaction as below.
- . T1: Read A → Write A→ Read B → Write B`
- • `T2: Read B → Write B`
- • `T3: Read C → Write C→ Read D → Write D`
- • ` T4: Read D → Write D
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