mongodb find nested field

First, the index introductionIn MongoDB, indexes are used to support efficient queries. If there is no index, MONGODB must scan each document in the entire collection to find a matching document. However, if an appropriate index is established,

MongoDB is a well-known NoSQL document database, while Spring is a well-known open-source framework in the Java field. In addition to the IoC and AOP components that constitute the core of Spring, Spring also has a large number of sub-frameworks

MongoDB is one of the most widely used NoSQL (not-only SQL) engines in the world, ranking very well above the db, and is the May ranking:　　You can see that the previous four are traditional relational databases, and MongoDB is the first in NoSQL.

MongoDB Practice Notes for beginners-install, create databases, save and query data, and learn mongodb MongoDB is a scalable and High-Performance Distributed Document storage database written in C. It is designed to provide scalable and

Find () methodTo query data from a MongoDB collection, you need to use MongoDB's find() method.Grammarfind()The basic syntax of the command is as follows:>db.COLLECTION_NAME.find(document)Shellfind()Method will display all documents in an

When it comes to MongoDB's architecture, it is inevitable to compare it with relational databases. Here we take MySQL for example, we make some comparisons:From the logical structure of the comparison: MySQL Hierarchy concept

I. Description 1, the study of the series MongoDB learning environment using the MongoDB version of mongodb-win32-i386-2.4.6, operating system for Win7. Second, installation 1, new two directories, respectively,

Mongodb1.1 Software Introduction? A product between a relational database and a non-relational database– a database based on distributed file storage.– written in the C + + language. Designed to provide scalable, high-performance data storage

Indexes can often greatly improve the efficiency of queries, and if there is no index, MongoDB must scan every file in the collection and select those records that meet the query criteria when reading the data. This scan full set of query efficiency

Some basics forget to check at any time.#整备恢复Mongodump--port 20001--authenticationdatabase=admin-u *-D lvlv-c lvlv-o/homeMongorestore--drop--host 172.16.201.74--port 20001--authenticationdatabase=admin-umgbackup-d test/tmp/liding/test