Object Oriented Database Model
- It maintains correspondence between real world and database objects without loosing integrity and identity
- Object has state and behavior
- Entity is represented as a class.
- Instances of the class are objects.
- Within an object , the class attributes takes specific values.
Object relational mapping (ORM)
- ORM is a programming technique for converting data between incompatible type systems into object oriented programming language.
- This creates a virtual object database , which can be used from within the programming language.
- It is necessary because objects are almost non-scales values while the DBMS can only store and manipulate scalar values organized within tables.
- ORM convert object values into group of singular values for storages in the database.
Properties of Parallel and Distributed Databases
Distributed Database system
- The database is stored on several computers known as sites.
- Each site is largely coupled.
- There is no any stored physical component.
- Communication between sites is done with network.
- Local transaction access data only from site where it was initiated.
- Global transaction access data from different sites.
Reasons for building distributed database system
- Users at one site is able to access data residing at other sites.
-Each site is able to retain a degree of control over ata that are stored locally. It has global administrators and local administrators.
-Even if one site fails, the other sites are functional with data replication on several sites, failure of a site does not affect the system.
Disadvantages
- High complexity for coordination among sites.
- Expensive software development cost
- High potential for bugs
- Increase processing overhead.
heterogeneous database
- Each site uses different schema.
- Difficulty in query and transaction processing.
- Provide limited facility for cooperation
homogeneous database
- All sites have identical dbms software
- Agree to cooperate in processing user requests.
- Each site surrender part of anatomy as a right to change schema
- It appears as a single system for users.
data replication
- Approach to store distributed data in which system contains multiple copies of data in different sites.
- Full replication indicates storing at all sites,
- Fully redundant indicates each site having entire copy of database.
- It ensures availability ,parallelism and reduced data transfer
- Update cost is high
- Difficult for concurrency control
data fragmentation
- Approach to store distributed in which relation r is divided.
- Fragments with sufficient information to reconstruct r
- Each schema should have common candidate key to ensure lossless join.
- In horizontal each tuple of r is assigned to one or more fragments
- It allows parallel processing and easy access.
- In vertical schema is split into several smaller schemes
- It allows parallel processing on relation
Parallel database system
- It contains multiple processors and multiple disks connected by a fast interconnection network.
- It improves processing and I/O speeds.
- Many operations are performed simultaneously.
- Coarse grain consists for powerful processors.
- Fine grain consists of thousand of smaller processors.
- Performance is measured using throughput and response time.
- Running a given task in loss time by increasing parallelism is called speedup.
- Handling a larger tasks by increasing parallelism is called scaleup.
- Speed up is linear if equals to N while scaleup is linear if equals to 1
- Speedup = (small system elapsed time) / large system elapsed time
- Scaleup = small system small task ET / Large system large task ET
Shared memory architecture
- Processors and disks share a common memory via bus or network
- Provides efficient inter-processor communication.
- Can not be scaled for more processors.
Shared data architecture
- All processors have access to all disk via network.
- Each processor has private memory.
- If one processor fails , others can recover the system.
- Processor communication becomes slower.
Shared nothing architecture
- Each processor has its own memory and disks.
- Communication between processor is via a network .
- It minimizes interference of resource sharing.
- Cost for communication and non-local disk access is high.
Hierarchical
- Combines all the architectures.
Data Warehousing
- Datawarehouse is a single ,complete and consistent data store obtained from a variety of sources made available to end users in the understandable form and used as a business context.
- It is subject oriented, integrated , time-variant and non-volatile collection of data to support decision making process.
Rules of data warehouse.
- separated from operational environment .
- data is integrated.
- contains historical data over a long period of time.
- data is subject oriented.
- mostly read only with periodic batch updates.
- Data contains levels of details , current old highly summarized .
- metadata is critical component.
- contains chargeback mechanism for resource usage.
Phases of data mining
- Data preparation
- data analysis and classification
- knowledge acquisition.
- prognosis (predict future behavior)
Need for data warehouse
- huge amt of operational data to be used for strategic decision making
- provides historical data for analysis.
- stores good quality data.
Application areas
- online analytical processing (OLAP )
- decision support system (OSS)
- Data mining
Warehouse architecture
- warehouse server
- olap server
- clients (query tool,analysis tool,data mining tool )
Spatial Database
- It is a database system with additional capabilities for handling spatial data.
- It provides spatial data types .
- It also supports relationships among SOT.
- Spatial data is the information about physical object that can be represented by numeric values in geographic coordinate.
1) Application areas
a. Geographical information system.
b. Environmental system.
c. Corporate decision support system.
d. Battlefield soldier monitoring system.
2) Modelling
a. Spatial objects
i. Point: represent object by its location in space
ii. Line: represent connection in space
iii. Region : represent extent in 2d space
b. Coverages
i. Partition : set of region objects
c. Networks
i. Graph consisting of set of points and line object
d. Spatial relationships
i. Topological : adjacent,inside
ii. Direction : above ,below
iii. Metric : distance
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