MongoDB에서 내부 조인 질의 표현에 대한 연구

Abstract

Recently, NoSQL database systems have been actively used to distribute and manage large-scale data. In particular, the MongoDB database system developed based on the document model using JSON format documents as the basic unit of data storage is the most widely used. MongoDB supports denormalization and normalization models to express the correlation between data, but from the viewpoint of query processing performance, the denormalization model, which expresses related data by embedding it in a single document, is recommended as the optimal method. However, since the denormalization modeling method cannot be optimal in all cases, the $lookup operation is provided to support the association between data in the form of a join of two documents, but this operation supports only the left outer join operation. In this study, we examine how the most commonly used inner join operation can be expressed in MongoDB. In particular, it introduces cases that can express inner joins using various operation functions currently provided by MongoDB without introducing additional new operations, and describes experimental evaluations thereof.