Basics - A Historical Perspective
- File Systems v/s DBMS
- Data Models
- Levels of Abstraction
- Structure of DBMS
- Database Design
- Database Design
- ER Diagrams
- Attributes
- Entity
- Relationships
- Additional Features of the ER Model
- Relational Model
- Introduction to the Relational Model
- Integrity constraint over relations
- Enforcing Integrity Constraints
- Querying Relational Data
- Views
- Relational Algebra
- Tuple Relational Calculus
- SQL
- Form of basic SQL query
- UNION
- INTERSECT
- EXCEPT
- Aggregation Operators
- Complex Integrity Constraints in SQL
- Triggers and Active data bases
- Schema Refinement
- Problems caused by redundancy
- Decompositions and its problems
- Functional Dependencies and its reasoning
- Introduction to Normal Forms
- First Normal Form (1NF)
- Second Normal Form (2NF)
- Third Normal Form (3NF)
- Boyce-Codd Normal Form (BCNF)
- Fourth Normal Form (4NF)
- Fifth Normal Form (5NF or PJNF)
- Sixth Normal Form (6NF)
- Transaction
- Transaction Concept
- Transaction State
- Implementation of Atomicity and Durability
- Concurrent Executions
- Serializability
- Recoverability
- Implementation of Isolation
- Lock Based Protocols
- Timestamp Based Protocols
- Validation Based Protocols
- Multiple Granularity
- Recovery and Atomicity in dbms
- Recovery with Concurrent Transactions
- Indexing
- Data on External Storage
- File Organization and Indexing
- Cluster Indexes
- Primary Indexes
- Secondary Indexes
- Index data Structures
- Comparison of File Organizations, Indexes and Performance Tuning
- Indexed Sequential Access Methods
- Dynamic Index Structure - B+ Tree
Transaction Concept in DBMS
A transaction is a single, logical unit of work that consists of one or more related tasks. A transaction is treated as a single, indivisible operation, which means that either all the tasks within the transaction are executed successfully, or none are.
Here are a few key properties of transactions, often referred to by the acronym ACID:
ACID Properties
- Atomicity
- Consistency
- Isolation
- Durability
Atomicity: This property states that a transaction must be treated as an atomic unit, that is, either all of its operations are executed or none. There is no such thing as partial transaction; if a transaction fails, all the changes made in the database so far by that transaction are rolled back, and the database remains unchanged.
Consistency: The database must remain in a consistent state after any transaction. No transaction should have any adverse effect on the data residing in the database. If the database was in a consistent state before a transaction, then after execution of the transaction, the database must be back to its consistent state.
Isolation: Each transaction is considered independent of other transactions. That is, the execution of multiple transactions concurrently will have the same effect as if they had been executed one after the other. But isolation does not ensure which transaction will execute first.
Durability: The changes made to the database by a successful transaction persist even after a system failure.
Next Topic :Transaction State in DBMS