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1
Q

What does OLTP stand for?

A

Online Transactional Processing

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2
Q

What does OLAP stand for?

A

Online Analytical Processing

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3
Q

What is a data warehouse primarily used for?

A
  • Business Intelligence
  • Analytics
  • Reporting
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4
Q

What is a data lake primarily used for?

A
  • Big Data
  • Machine Learning
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5
Q

What type of data is stored in a data warehouse?

A

Structured

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6
Q

What type of a data is stored in a data lake?

A

Structured, semi-structured, unstructured

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7
Q

What is a data lakehouse primarily used for?

A

Combines the querying capabilities of a data warehouse with the schema-less nature and high storage capacity of data lakes.

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8
Q

What does ACID stand for?

A

Atomicity, Consistency, Isolation, and Durability

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9
Q

What does CRUD stand for?

A

Create, Read, Update, Delete

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10
Q

What does Atomicity in ACID mean?

A

Ensures that all operations in a transaction are fully completed.

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11
Q

What does Consistency in ACID mean?

A

Guarantees the database remains valid before and after a transaction.

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12
Q

What does Isolation in ACID mean?

A

Ensures transactions run independently without affecting each other’s outcome.

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13
Q

What does Durability in ACID mean?

A

Once a transaction is committed, it stays permanent.

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14
Q

What is the 1NF (First Normal Form)?

A

All records have the same structure (same number of fields) and each field contains a single value, with no repeating groups of data.

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15
Q

What is the 2NF (Second Normal Form)?

A

A non-key field must provide a fact about the key, us the whole key, and nothing but the key.

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16
Q

What is the 3NF (Third Normal Form)?

A

Non-key fields only depend (describe) the primary key and not other non-key fields.

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17
Q

What is data governance?

A

The overall management of data availability, usability, integrity, and security.

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18
Q

What is sharding?

A

Distributing data across multiple database instances or servers.

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19
Q

What are the benefits of sharding?

A

Can handle high volumes of traffic and allows for parallel processing.

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20
Q

What does the acronym CAP (CAP theorem) stand for?

A

Consistency, Availability, Partition Tolerance

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21
Q

What does the CAP theorem state?

A

In a distributed data store, you can only guarantee two of the three properties.

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22
Q

What is data modeling?

A

The process of creating a conceptual representation of data and its relationships within a database.

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23
Q

What is data transformation?

A

The process of converting data from its original format into a format suitable for analysis or processing.

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24
Q

What are common techniques used in data transformation?

A
  • Data cleansing
  • Data normalization
  • Aggregation
  • Data mapping
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25
What is a Star Schema?
A central fact table connected to dimension tables in a simple, denormalized structure for fast querying.
26
What is a Snowflake Schema?
A normalized version of the star schema with dimension tables further split into related tables to reduce redundancy.
27
What is data lineage?
Tracking of the flow and transformation of data throughout its lifecycle.
28
What is a data mart?
A subset of a data warehouse, focused on a specific business line or team.
29
What are OLTP systems typically used for?
Real-time transactional processing, such as banking, ecommerce, or bookings.
30
What are OLAP systems typically used for?
Processing and analyzing large amounts of data quickly for business intelligence and reporting.
31
What does DSA stand for?
Data Structure Analysis
32
How do you optimize queries?
* Analyze execution plan with EXPLAIN * Build indexes * Minimize SELECT columns * Refactor complex queries
33
How do you ensure data quality throughout a pipeline?
* Unit testing code * Retries for transient errors * Data quality validation (great expectations) * Monitoring and alerting
34
What does ETL stand for?
Extract, Transform, Load
35
What does ELT stand for?
Extract, Load, Transform
36
Are python "lists" mutable or immutable?
Mutable
37
How do you add an item to a python "list"?
``` list.append(item) ```
38
How do you insert an item into a python "list"?
``` list.insert(index, element) ```
39
How do you remove an item from a python "list"?
``` list.remove(item) ```
40
How do you slice a python "list"?
``` list.slice(start:stop:step) ```
41
Provide an example of "list comprehension" in python.
``` [ x * 2 for x in list ] ```
42
Is a python "tuple" mutable or immutable?
Immutable
43
Provide an example of python "tuple" unpacking.
``` a, b, c = tuple ```
44
Provide an example of setting a "tuple" in python.
``` tuple = (1, 2, 3) ```
45
Are python "dictionaries" mutable or immutable?
Mutable
46
Provide an example of setting a python "dictionary".
``` dictionary = { 'key1': 'value1', 'key2': 'value2' } ```
47
Provide an example of adding/updating a python "dictionary" value.
``` dictionary[key] = value ```
48
Provide an example of removing a python "dictionary" value.
``` dictionary.pop(key) ```
49
Provide an example of accessing a python "dictionary" keys.
``` dictionary.keys() ```
50
Provide an example of accessing a python "dictionary" values.
``` dictionary.value() ```
51
Provide an example of python "dictionary" comprehension.
``` { k: v * 2 for k, v in dictionary.items() } ```
52
Are python "sets" mutable or immutable?
Mutable, but unique
53
Provide an example of setting a python "set".
``` set = {1, 2, 3} ```
54
Provide an example of adding an item to a python "set".
``` set.add(item) ```
55
Provide an example of removing an item from a python "set".
``` set.remove(item) ```
56
Provide an example of a python "set union" operation.
``` { set_1 | set_2 } ```
57
Provide an example of a python "set intersection" operation.
``` { set_1 & set_2 } ```
58
Provide an example of a python "set difference" operation.
``` { set_1 - set_2 } ```
59
Provide an example of python "set" comprehension.
``` { x * 2 for x in set if x > 2 } ```
60
Provide an example of setting a "name tuple" in python.
``` tuple = namedtuple('Point', ['x', 'y']) ```
61
Provide an example of using a "named tuple" in python.
``` p = Point(1, 2) print(p.x, p.y) ```

Data Engineer (4 decks)

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