Govt Exams
Indexes speed up data retrieval by creating optimized lookup structures, reducing the number of disk accesses needed to find data.
IaaS provides infrastructure resources (compute, storage, networking). SaaS provides applications, PaaS provides development platforms.
INNER JOIN returns only rows with matches in both tables. LEFT JOIN returns all rows from the left table plus matching rows from the right table.
A heap (binary heap) efficiently implements priority queues with O(log n) insertion and deletion of minimum/maximum elements.
ACID properties ensure reliable database transactions: Atomicity (all-or-nothing), Consistency (valid state), Isolation (concurrent independence), Durability (permanent storage).
Relational databases store structured data in tables. Unstructured data is typically stored in NoSQL or document databases.
Hash collisions occur when two different keys hash to the same table index. Resolution techniques include chaining and open addressing.
DROP removes the entire table structure and data. DELETE removes only data. TRUNCATE removes data but is faster than DELETE.
Binary search divides the search space in half with each iteration, resulting in logarithmic time complexity O(log n).
3NF removes transitive dependencies where a non-key attribute depends on another non-key attribute. BCNF is stricter but 3NF is the standard answer for eliminating transitive dependencies.