All Content Flashcards
Enterprise Information Systems focus on integration. Which are the 3 types of integration?
- Data/Information Integration
- Enterprise Application Integration
- Business-to-business Integration
Which is the goal of integration?
Provide a homogeneous, integrated view on multiple, distributed, autonomous and heterogeneous systems, components, or data sources.
Which are the 3 fundamental challenges of integration?
- Distribution
- Autonomy
- Heterogeneity
Which are the 2 types of distribution?
- Logical
- Physical
Which are the 4 types of autonomy?
- Design
- Interface
- Access
- Judicial
Which are the 2 main approaches to resolve heterogeneity?
- When needed
- Enforce by establishing standards
Which are the 6 types of heterogeneity?
- Technical
- Data Model
- Syntactic
- Structural
- Schematic
- Semantic
Which are the 2 architectural approaches to achieve data integration?
- Materialized integration: replication, data warehousing
- Virtual integration: federated DBMS, multi-DB systems
Which are the 4 characteristics of DDBMS?
- Distribution by design
- 4-layer schema architecture
- Tightly couple
- Heterogeneity not an issue
Which are the 4 characteristics of FDBMS?
- Provides homogeneous and integrated view of data from multiple sources (federated conceptual schema)
- “On-Demand” data integration
- Requires: wrapper/mediator technology, data and schema integration mechanisms
- Distribution is given
- Preserves high degree of autonomy
Which are the 2 alternatives for federated schema creation?
- bottom-up: schema integration
- top-down: schema design, schema mapping
Which are the 5 layers of the Schema Reference Architecture?
- external schema
- federated schema
- export schema
- component schema
- local schema
Mediator-based IS are a generalization of DDBMS and FDBMS. Which are the 2 main components?
- wrappers
- mediator
Which are the 4 tasks of wrappers?
- encapsulate data source for uniform access
- help overcome heterogeneity of data sources
- support global query evaluation and optimization
Which are the 3 main characteristics of Garlic?
- Garlic and wrappers cooperator for query processing
- Extensibility
- Wrapper evolution (until provide full support of data source functionality)
Which are the 4 wrapper services of Garlic?
- modelling data as object collection
- method calls
- query planning
- query execution
Garlic optimizer builds query plan using bottom-up approach. Which are the 4 steps?
- create plan fragments for single collections
- plan the join processing for local joins
- plan the join processing across multiple sources
- finalize the plan (compensations)
Which are the 3 methods that wrappers provide to Garlic work requests?
- plan_access( )
- plan_join( )
- plan_bind( )
Which are the 4 characteristics of MDBMS?
- loosely coupled
- no global schema
- multi-database language
- only location and physical distribution transparency
- data model heterogeneity handled by local data source or multi-db language
What is the limitation of SQL to solve most forms of schematic heterogeneity?
Views can be used under certain specific circumstances. Otherwise the maintenance is expensive.
Which are the 3 characteristics of Schematic Query Languages to deal with schematic heterogeneity?
- Transform data to metadata (and v.v.)
- Extend relational model to allow dynamic schemas
- mechanism to access different DBs in a single query
Which is the main idea of SchemaSQL?
Extended FROM clause: ->, db->, db::rel->, db::rel, db::rel.attr
Which are the 2 points of criticism over SchemaSQL?
- merge not well-defined for all source relations
- semantics of SELECT differs depending on context
Which is the main idead of FIRA/FISQL?
Provide federated relational model with additional algebra operators.
Which are the 6 new operator of FIRA/FISQL?
- Drop-projection
- Down
- Attribute Dereference
- Generalized Union
- Transpose
- Partition operator
Which are the 2 motivations for replication?
- increase availability
- increase performance
Which are the 3 challenges for replication?
- transaction processing
- enforcing consistency
- detecting and resolving conflicts
Which are the 2 types of replication?
- eager replication
- lazy replication
Which are the advantages and disadvantages of eager replication?
\+ guarantees globally serializable execution \+ avoid inconsistencies - deadlocks - lack of scalability - cannot be used if nodes offline
Which are the advantages and disadvantages of lazy replication?
\+ minimal update overhead \+ works if nodes offline - stale data - conflicting updates may cause inconsistencies - potential for system delusion
Which are the 2 ways of bidirectional replication?
- master/slave
- peer-to-peer
Which are the 2 replication methods?
- Target table refresh
- Change-capture
Which are the 4 types changes can be capture for replication?
- continuous
- interval-based
- DB events
- one-time snaptshot
Which are the 2 realization approaches for capturing data?
- analyze DB log files
- use DB triggers