mongodb explain index

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First, index MongoDB provides a variety of index support, indexed information is kept in system.indexes, and the default is always to create an index for _id, which uses the same relational database as MySQL. In fact, it can be said that the index

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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

First, IntroductionIndexing in MongoDB can improve query efficiency, only need to scan the index only a small portion of this collection, and only to load this small part into memory, the efficiency greatly improved, if not indexed, in the query,

Learning MongoDB 8: MongoDB index (index restrictions) (2), mongodb IndexI. Introduction In the previous article, we introduced basic index operations through db. collection. the createIndex (keys, options) syntax creates an index. We will continue

Previous wordsIndexes 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

MongoDB data model and index learning summary, mongodb ModelMongoDB data model and index learning Summary 1. MongoDB Data Model: MongoDB data storage structure:MongoDB uses BSON (binary json, binary encoding) data format for document (large files

Index can improve the performance of the query, if no INDEX,MONGODB must scan the entire collection, starting with the first doc of collection, until the last doc, even if all doc after the first Doc does not meet the query criteria. If there is a

I. Index 1, index operation 1.1 inserting data> use testdbswitched to db testdb> for (i=1;i db.students.find().count()100001.2 Creating an Index在name字段构建升序索引：> db.students.ensureIndex({name: 1}){ "createdCollectionAutomatically" : false,