IDS Key Concept Terms

What’s the difference between data and information?

Data = raw facts.

Information = organized and useful.

What is a data lake?

Big storage for raw, mixed data types.

Not ready for users until processed.

Operational vs Analytical systems?

Operational = Used now, fast.

Analytical = Used later, for trends and analysis.

Types of data structure?

Structured = Same format.

Unstructured = Different every time.

Semi-structured = Mix of both.

What is a relational database?

Uses tables with rows and columns.

All records follow same format. Tables link using foreign keys.

What is ACID in databases?

Atomicity = All or none.

Consistency = Follow rules.

Isolation = Tasks stay separate.

Durability = Changes stay saved.

What is NoSQL?

Non-relational, flexible storage.

Types: Key-Value, Document, Graph.

What’s schema stability?

Relational = Fixed table layout.

Rarely changes. Good for consistency.

What’s referential integrity?

Foreign key must match a primary key.

What’s a join?

Combine data from two related tables.

What is a distributed database?

Data stored on many machines.

Handles big data volume.

What is MapReduce?

Map = Split job.

Reduce = Combine results.

Difference between Hadoop and Spark?

Hadoop = Slower, disk-based.

Spark = Faster, RAM-based.

Why use distributed systems?

Too much data for one server.

Needed for speed and size.

What is N-tier architecture?

Layers: Client → App → Database.

Easier to scale and upgrade.

What is in-memory database concept (TimesTen)?

Data stored in RAM for speed.

Written to disk later.

What’s a document database?

Flexible, stores data like JSON.

Good for unstructured content.

What is eventual consistency?

Data copies may mismatch for a while.

System fixes them later.

What is a wide-column database?

Data stored in columns.

Good for large, semi-structured data.

What’s a graph database?

Stores records plus their connections.

Good for social networks.

What is SQL?

Language for talking to databases.

4 SQL command groups?

DDL = Define tables.

DML = Change data.

DQL = Read data

DCL = User permissions.

What’s a SELECT query?

Pulls specific data from a table.

What is a WHERE clause?

Filters which rows to affect.

What’s LIKE and Wildcards?

LIKE = Search by pattern.

* = Select all.