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UGC NET Computer Science Database Management Systems Flashcards
53 question-and-answer cards covering Database Management Systems as it is examined in UGC NET Computer Science. 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the Database Management Systems deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
What are the main algorithms for implementing a join in query processing?
Nested-loop join, block nested-loop join, index nested-loop join, sort-merge join, and hash join.
State the ACID properties of a transaction.
Atomicity (all-or-nothing), Consistency (preserves integrity constraints), Isolation (concurrent transactions don't interfere), and Durability (committed changes survive failures).
What are the states in a transaction's life cycle?
Active, Partially Committed, Committed, Failed, and Aborted (terminated).
What is a schedule, and what makes it conflict-serializable?
A schedule is an interleaved order of operations of concurrent transactions. It is conflict-serializable if it can be transformed into a serial schedule by swapping non-conflicting adjacent operations — testable via an acyclic precedence (conflict) graph.
What is the two-phase locking (2PL) protocol?
A concurrency-control protocol where each transaction acquires all locks in a growing phase and releases locks only in a shrinking phase (no lock acquired after the first release), which guarantees conflict serializability.
What problems do concurrency-control techniques prevent?
The lost update problem, the dirty read (temporary/uncommitted dependency) problem, the unrepeatable read problem, and the incorrect summary (phantom) problem.
Compare deadlock prevention schemes wait-die and wound-wait.
Both use timestamps. Wait-die: an older transaction waits for a younger one, a younger one requesting an older's lock dies (non-preemptive). Wound-wait: an older transaction preempts (wounds) a younger one, a younger one waits (preemptive).
Differentiate deferred and immediate database update recovery techniques.
Deferred update: changes are written to the database only after commit (no UNDO needed, only REDO). Immediate update: changes may be written before commit, requiring both UNDO and REDO using the log.
What is the write-ahead logging (WAL) protocol?
Before any data page modification is written to disk, the corresponding log (UNDO) record must first be forced to stable storage, and the commit log record must be written before commit completes — ensuring atomicity/durability.
What is a checkpoint in database recovery?
A point at which the DBMS flushes buffers/log to disk and records a checkpoint marker, limiting the amount of log that must be scanned during recovery to transactions active at or after the checkpoint.
How do object-oriented databases differ from object-relational databases?
OODBs store objects natively with identity, inheritance, and methods using an object data model. ORDBs extend the relational model with object features (user-defined types, inheritance, references) while retaining SQL and tables.
What is the difference between authentication and authorization in database security?
Authentication verifies a user's identity (who you are); authorization (via GRANT/REVOKE privileges) determines what operations/data that identity is permitted to access.
Compare Discretionary (DAC) and Mandatory (MAC) access control in databases.
DAC grants/revokes privileges at the owner's discretion (GRANT/REVOKE). MAC enforces system-wide security classes/clearances (e.g., Bell-LaPadula) preventing flow from higher to lower classifications.
What are valid time and transaction time in a temporal database?
Valid time is the period during which a fact is true in the real world; transaction time is the period during which the fact was stored as current in the database. A bitemporal database records both.
What is a deductive database and which language is associated with it?
A deductive database can derive new facts (rules) from stored facts using logic. It typically uses Datalog (a Prolog-like declarative rule language) with facts and rules to infer intensional data.
What role does XML play in internet databases, and how is XML data queried?
XML provides a self-describing, hierarchical, platform-independent format for exchanging semi-structured data over the web; it is queried/navigated using XPath and XQuery (with XSLT for transformation).
What are the key characteristics (the Vs) of Big Data?
Volume (scale), Velocity (speed of generation/processing), Variety (structured, semi-structured, unstructured), Veracity (uncertainty/quality), and Value.
What are the two phases of the MapReduce programming model?
Map: processes input key-value pairs to produce intermediate key-value pairs. Reduce: aggregates all intermediate values grouped by key to produce the final output (with a shuffle/sort between the phases).
In HDFS, what are the roles of the NameNode and DataNode?
The NameNode is the master that manages the filesystem namespace and metadata (block locations); DataNodes are workers that store the actual data blocks and serve read/write requests. Blocks are replicated (default 3x) for fault tolerance.
Differentiate OLTP and OLAP systems.
OLTP: transaction-oriented, many short read/write operations, normalized schema, current data, day-to-day operations. OLAP: analysis-oriented, complex read-mostly queries, denormalized/star schema, historical aggregated data for decision support.
Differentiate star schema and snowflake schema in data warehouse modeling.
Star schema: a central fact table linked to denormalized dimension tables (simple, fast queries). Snowflake schema: dimension tables are normalized into sub-dimensions (less redundancy, more joins).
In association rule mining, define support, confidence, and lift.
Support(X) = fraction of transactions containing X. Confidence(X→Y) = support(X∪Y)/support(X). Lift(X→Y) = confidence/support(Y); lift > 1 indicates positive correlation. The Apriori algorithm uses these to find frequent itemsets.
Contrast supervised classification, regression, and unsupervised clustering in data mining.
Classification predicts a discrete categorical label from labeled data; regression predicts a continuous numeric value from labeled data; clustering groups unlabeled data into natural groups by similarity (no predefined labels).
How do the k-Nearest Neighbour and Support Vector Machine classifiers work?
kNN is a lazy, instance-based method classifying a point by the majority class of its k nearest neighbours. SVM finds the optimal separating hyperplane that maximizes the margin between classes, using kernels for non-linear boundaries.
What this deck covers
The Database Management Systems deck follows the UGC NET Computer Science Database Management Systems syllabus — 8 chapters and 51 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 6.6 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 199 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
Database Management Systems flashcards FAQ
How many Database Management Systems flashcards are in this UGC NET Computer Science deck?
53 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these UGC NET Computer Science flashcards free?
Yes. The preview here is free to read with no signup, and the full 53-card deck is free inside the Examius app.
What do the Database Management Systems cards cover?
They follow the UGC NET Computer Science Database Management Systems syllabus — 8 chapters and 51 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.