Parallel and Distributed Databases are designed to improve performance and reliability by using multiple processors or computers.
Parallel Databases:
A parallel database is a type of database system that uses multiple processors and storage devices working in tandem to perform database operations such as query processing, data storage, and indexing more efficiently.
- By dividing large tasks into smaller sub-tasks and executing them concurrently, parallel databases significantly reduce the time required for processing large datasets.
- Parallel databases are commonly used in high-performance computing environments where speed and processing efficiency are critical.
There are three primary types of parallel architectures:
- Shared-Memory Systems:
- All processors share the same physical memory and disk. Tasks are divided and executed simultaneously using threads.
- Shared-Disk Systems:
- Each processor has its own memory but shares common disk storage. All nodes can access the data, allowing concurrent data processing.
- Shared-Nothing Systems:
- Each processor has its own memory and disk. It operates independently and communicates with others through a network. This model is highly scalable and fault-tolerant.
Distributed Databases:
A distributed database is a collection of databases stored at different physical locations, often across multiple geographical regions, but connected via a network.
- Despite being physically distributed, the system is designed to appear as a single logical database to the user.
- They aim to improve reliability, availability, and scalability by decentralizing data storage and processing.
They rely on several key features:
- Data distribution:
- Data is divided into fragments and stored in different locations, which may improve performance and fault tolerance.
- Replication:
- Copies of data are stored at multiple sites to ensure high availability and prevent data loss in case of hardware or network failure.
- Consistency and concurrency:
- Distributed databases need mechanisms to maintain consistency and handle concurrent access across the distributed system.
Comparison: Parallel vs. Distributed Databases:
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