Architecture and Classification
5 important questions on Architecture and Classification
Query processor? And components
DML Compiler: compiles DML statements
Query parser: parses query into internal representation format + checks syntactical and semantical correctness
Query rewriter: optimizes query, independently of current database state.
Query optimizer: optimizes the query based on current database state. Varies execution plans and their time/cost.
Query executor: takes care of the final execution plan. Calls storage manager for data requested
Procedural vs declarative DML?
- explicitly specifies how to navigate
- record at a time
- no query processor
DECLARATIVE
- specifies what data should be retrieved
- set at a time
- query processor
Storage manager and components?
Transaction manager: supervises executions, creates a schedule of read/write, guarantees ACID. Commit transactions and rollback when unsuccessful
Buffer manager: manages bugger memory, smart replacement strategy in case buffer is full. Frequent requests
Lock manager: provides concurrency control, ensures integrity. Read and write locks via protocol and table
Recovery manager: supervises correct execution of transactions, keeps track of operations in a log file. Can be called to undo actions of aborted transactions
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What are the DBMS utilities?
Reorganization
Performance monitoring
User management
Backup and recovery
DBMS catigorizatio based on architecture?
- data on a central server
Client-server
- active clients request services from passive servers.
- Fat server versus fat client variant
N-tier:
- client with GUI functionality, application server with applications, database server with database, web server with access
Cloud:
- dbms and database are hosted by a third party cloud
Federated:
- provides a uniform interface to multiple underlying data sources.
- Hides the underlying storage details to facilitate data access
In-memory:
- stores all data in internal memory instead of slower external storage.
- Often for real-time purposes
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