A data lake is a centralized storage repository designed to hold vast amounts of raw data in its native format. The fundamental principle of a data lake is to ingest and store data "as-is" from various sources without prior transformation or structuring (a concept known as schema-on-read). This approach preserves the original, unaltered data, making it available for diverse and future analytical purposes. In contrast, other repositories like data warehouses require data to be cleaned, transformed, and structured into a predefined schema before it is loaded (schema-on-write), thereby altering it from its original state.

B. Data warehouse: Stores structured and transformed data that has been processed (ETL/ELT) to fit a predefined schema, meaning it is not in its original, unaltered form.

C. Data table: A specific structure within a database that holds organized, structured data, which by definition has been processed to fit the table's schema.

D. Data factory: A cloud service for orchestrating and automating data movement and transformation (ETL/ELT pipelines); it is a processing tool, not a storage repository.

1. Microsoft Azure Documentation. (2023). What is Azure Data Lake?. "A data lake is a centralized repository that allows you to store all your structured and unstructured data at any scale. You can store your data as-is

without having to first structure the data..."

2. Amazon Web Services (AWS) Documentation. (n.d.). What is a Data Lake?. "A data lake is a centralized repository that allows you to store all your structured and unstructured data at any scale. You can store your data as is

without having to first structure the data..."

3. Nargesian

F.

Ghafori

E.

Toosi

A.

& van der Aalst

W. M. P. (2019). Data Lake Governance: A Survey. ACM Computing Surveys

52(4)

Article 80

p. 2. "A data lake is a storage repository that holds a vast amount of raw data in its native format until it is needed." DOI: https://doi.org/10.1145/3342260

4. Hai

R.

Geisler

S.

& Quix

C. (2016). Constance: An Intelligent Data Lake System. In Proceedings of the 2016 International Conference on Management of Data (SIGMOD '16). Association for Computing Machinery

New York

NY

USA

2097–2100. Section 2

"Data Lakes". "Data lakes keep the data in its raw format and only apply a schema when the data is read (schema-on-read)." DOI: https://doi.org/10.1145/2882903.2903740