Review
- 2023-07-03 23:38
一、Introduction #
001、URL vs URI vs URN #
URI #
URI stands for Uniform Resource Identifier. It identifies a logical or physical resource on the web. URL and URN are subtypes of URI. URL locates a resource, while URN names a resource.
A URI is composed of the following parts:
scheme:[//authority]path[?query][#fragment]
URL #
URL stands for Uniform Resource Locator, the key concept of HTTP. It is the address of a unique resource on the web. It can be used with other protocols like FTP and JDBC.
URN #
URN stands for Uniform Resource Name. It uses the urn scheme. URNs cannot be used to locate a resource. A simple example given in the diagram is composed of a namespace and a namespace-specific string.
002、What are the differences between a data warehouse and a data lake? #
A data warehouse processes structured data, while a data lake processes structured, semi-structured, unstructured, and raw binary data.
A data warehouse leverages a database to store layers of structured data, which can be expensive. A data lake stores data in low-cost devices.
A data warehouse performs Extract-Transform-Load (ETL) on data. A data lake performs Extract-Load-Transform (ELT).
A data warehouse is schema-on-write, which means the data is already prepared when written into the data warehouse. A data lake is schema-on-read, so the data is stored as it is. The data can then be transformed and stored in a data warehouse for consumption.