What does schema-on-read permit?

Schema-on-read allows for flexibility in how data is interpreted when it is accessed, rather than when it is stored. This approach enables users to define the structure of data at access time, which is particularly useful when dealing with large volumes of unstructured or semi-structured data. By defining the schema at the point of reading the data, it supports various analytical and querying methods without the need to conform the data to a predefined schema beforehand. This adaptability is especially beneficial in environments where data types and structures may vary widely, making real-time analysis and insights more achievable.

In contrast, defining data structure at write time would be characteristic of a schema-on-write model, which requires a fixed schema before data can be stored. The alteration of data post-creation and modification of existing schemas pertain to changing data after it has been initially defined, which is not the primary focus of schema-on-read.