IPA FE Subject A sample Question 23

A question IPA Japan published in 基本情報技術者試験科目A サンプル問題問23, translated into English. ITPEC is based on the same exams.

Which of the following is an appropriate characteristic of a data lake, which is a place where big data is stored?

a)All kinds of data are stored in their original formats and structures.b)To reduce the amount of data, metadata, which is descriptive information about the data, is not stored.c)Before data is stored, how the data will be used is designed, and the schema is defined in advance accordingly.d)Different repositories are used according to the format of the data to be stored, such as text files and binary data.

Explanation

Stores all data as it is — a data lake keeps raw data in its original form and decides how to read it later.

A data lake is a single repository that takes in data of every kind in its original format: structured tables, semi-structured data such as CSV, JSON and logs, and unstructured text, images and audio. A structure is applied only when the data is read for a particular analysis (schema-on-read), so data can be collected before anyone knows how it will be used.

Answer (a)

Why not others:

•(b) — a data lake does keep metadata: without descriptions of what each data set is, nobody can find or trust the data in it
•(c) — designing the use and fixing the schema before storing (schema-on-write) describes a data warehouse, not a data lake
•(d) — a data lake keeps all formats together in one repository instead of a separate repository per format

Key rule: A data warehouse is schema-on-write, cleaned and structured for known uses; a data lake is schema-on-read, raw data of every kind kept as it is.

Databases · AI-written, may contain errors

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This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.