Kleppmann, Martin

A relational data model uses tables that consist of rows and columns. A row can be uniquely identified by a table + ID combination. A column entry can reference another row in another table through a shared key. One goal is to avoid duplicating data. However, to answer a real-world query, we end up paying th cost by joining results from multiple tables. That said, with proper indexing and prior research, combining results is pretty fast....

Query Languages for Data If you have a list of animal species and you want to return only the sharks in the list, a relational algebra expression would be \( \text{sharks} = \sigma_{\text{family = “Sharks”}}(\text{animals}) \). SQL queries follow the structure of relational algebra closely: SELECT * FROM animals WHERE family = 'Sharks'; … while an imperative query would be: function getSharks() { let sharks = []; for (let i = 0; i < animals....

Relational Model Versus Document Model; Thinking About Data Systems; Designing Data-Intensive Applications [Kleppmann, Martin]; Query Languages for Data; Reliability; Maintainability; Scalability;