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DBMS → Introduction to DBMS 16

In DBMS terminology a schema is:
The overall design or logical structure of the database
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What is the instance of a database?
The actual data stored in the database at a particular moment in time
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Which component converts high-level queries into efficient low-level operations?
Query Optimizer
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What is data independence fundamentally protecting against?
The ripple effect of changes in one schema level propagating to another
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Which is a characteristic of an active database?
It can automatically trigger actions via triggers in response to database events
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In DBMS terminology a relation is equivalent to:
A table
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Which statement about NULL values is most accurate?
NULL represents an unknown, missing, or inapplicable value
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The ANSI/SPARC three-schema architecture was proposed primarily to achieve:
Data independence between different levels of database abstraction
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Which DBMS architecture is most suitable for internet-scale applications?
Three-tier architecture
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What distinguishes a primary key constraint from a unique constraint?
Primary key does not allow NULL values and must be unique; unique allows one NULL
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What is the primary purpose of a buffer manager in a DBMS?
Manages transfer of data between disk and main memory to minimize I/O
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Semantic integrity in DBMS refers to:
Ensuring data satisfies real-world constraints and business rules beyond syntactic correctness
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Which is a correct statement about ORDBMS?
ORDBMS extends the relational model with object-oriented features like user-defined types and methods
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What is the primary purpose of a transaction log in a DBMS?
To maintain a record of all database changes for recovery and rollback purposes
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What is a deductive database?
A database that uses rules to deduce new facts from stored facts
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In DBMS what is the data dictionary and why is it important?
A system repository storing metadata about all database objects used by the DBMS engine for query processing, optimization, and integrity enforcement
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DBMS → Database Architecture 24

In shared-nothing architecture what do nodes share?
Nothing - each node has its own memory, CPU and storage
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Which correctly describes shared-memory vs shared-disk architectures?
Shared-memory: all processors access one common memory; shared-disk: separate memories but common disk
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What is a federated database system?
A collection of autonomous heterogeneous database systems appearing as a single unified system
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What is the primary role of the storage manager in DBMS architecture?
Providing the interface between the high-level DML and low-level data storage
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In a two-tier client-server architecture what is a major limitation?
Business logic embedded in the client makes maintenance difficult
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What is middleware in a three-tier database architecture?
Software layer between the client presentation tier and the database tier handling business logic
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What is the primary advantage of connection pooling?
It reuses established database connections reducing overhead of creating new connections for each request
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The query processor in a DBMS consists of which components?
DDL interpreter, DML compiler, and query evaluation engine
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Which architectural pattern does Apache Hadoop use?
Shared-nothing architecture with MapReduce
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What is data sharding in distributed database architecture?
Horizontally partitioning data across multiple database nodes based on a shard key
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The CAP theorem states you can only guarantee at most two of:
Consistency, Availability, Partition Tolerance
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In a Lambda architecture the speed layer is responsible for:
Processing real-time streaming data to provide low-latency approximate results
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Column-store database architecture is better suited for OLAP because:
Storing values of each column contiguously enables high compression and allows reading only required columns reducing I/O for aggregation queries
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What is the purpose of Write-Ahead Logging (WAL)?
To ensure all changes are logged to disk before they are applied enabling recovery after failures
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What is the difference between synchronous and asynchronous replication?
Synchronous waits for replica confirmation before committing; asynchronous commits immediately and replicates later
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What is MVCC (Multi-Version Concurrency Control)?
A concurrency control mechanism that maintains multiple versions of data to allow reads without blocking writes
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What is the purpose of a materialized view?
Materialized views physically store precomputed query results improving performance at the cost of storage and refresh overhead
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In a distributed database the 2PC protocol is used to:
Ensure atomicity of distributed transactions across multiple database nodes
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What is the database-per-service pattern in microservices?
Each microservice owns its private database preventing direct access by other services
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What is the primary architectural difference between OLTP and OLAP systems?
OLTP optimizes for many short transactions with point lookups; OLAP optimizes for complex analytical queries over large datasets
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Which component is responsible for lock management in concurrent transactions?
Lock Manager (part of Concurrency Control Manager)
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What is the SAGA pattern in microservices database architecture?
It manages long-running distributed transactions without using 2PC using a sequence of local transactions with compensating transactions
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What is data partitioning and how does horizontal differ from vertical?
Horizontal partitioning splits rows across multiple partitions; vertical partitioning splits columns across multiple tables
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What is NUMA and how does it affect database architecture?
A memory architecture where processors have different latencies to different memory regions requiring NUMA-aware data placement
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