mongodb compass run query

amazing to see the question. But the actual look of the past has not changed.Determine if MongoDB used index intersection, run explain (); The results of explain () would include either an and_sorted stage or an and_hash stage. Merge sort or hash combination. Similar to join practices. Stages is descriptive of the operation; e.g. COLLSCANFor a collection scan IXSCANFor scanning index keys

Tags: style blog color using OS IO data issuesRecently, when using MongoDB, I encountered a scene with multiple keywords for fuzzy query. The bamboo wind uses the Mongoengine library.Looked up all kinds of information, and finally summed up the more useful methods. First, the code, followed by detailed instructions. As follows:1 #!/usr/bin/env python2 #Coding:utf-83 4 ImportRe5 ImportMongoengine6 fromMongo

Label:Go on to the next chapter and continue to introduce MONGODB queries. Querying on Embedded DocumentsThere are two ways to query embedded sub documents: Querying the entire document or querying individual key-value pairs. Querying the entire child document is the same as the normal query. We have a document: { "name": { "first": "Joe",

In MySQL, the slow query log is often used as our basis for optimizing queries, is there a similar function in MongoDB? The answer is yes, that is to open the profiling function. The tool collects write operations on MongoDB, cursors, database commands, etc. on the running instance, which can be opened at the database level or at the instance level. The tool writ

are completely different) {' Title ':' Xueyou ', ' Age ':+} {' age ':+, ' title ':' xueyou '} syntax: The key cannot contain the . Null character, which represents the end of the key . and $ have a special meaning, usually keep _ the keys that start with usually also want to keep, although not forcing MongoDb to differentiate between types also case -sensitive documents cannot have duplicate keys Collection 看做是表,多个文档组成集合 语法: 不能包含 \

command line tool, in fact, is also a JS interpreter, support JS syntax Mongod: The database server, each instance starts a process that can fork to run in the background. Mongodump/mongorestore: Data backup and recovery tools. Mongoexport/mongoimport: Data export and Import tool. MONGOFILE:GRIDFS management tool that enables binary file access. MONGOs: Shard Routing, if the sharding feature is used, the application connects MONGOs instead

. Combining $in and $not can achieve the same effect $nin. $or used to make or queries on multiple keys. Iii. Specific types of queries 1. Null query Null not only matches itself, but also matches a document where the key does not exist. 2. Regular expressions 3. Array query $all: Matches an array by multiple elements. $size: Queries the array of the specified length. $slice: Returns a sub-collection

Label:This article focuses on the paging query of MongoDB Traditional SQL Paging Traditional SQL paging, all the solutions are almost row_number, for the needs of a variety of sorting, complex query scenarios, Row_number is the killer. In addition, for the current web is very popular Poll/push load paging way, generally use time stamp to achieve paging. These two

Turn on slow query profilingProfiling level Description0: Close, do not collect any data. 1: Collect slow query data, default is 100 milliseconds. 2: Collect all data1. Open profiling by modifying the configuration fileTo modify the startup mongo.conf, insert the following code# turn on slow query, 200 ms record profile = 1= 2002, after the start of

used to make or queries on multiple keys. Iii. Specific types of queries 1. Null query Null not only matches itself, but also matches a document where the key does not exist. 2. Regular expressions 3. Array query $all: Matches an array by multiple elements. $size: Queries the array of the specified length. $slice: Returns a sub-collection of arrays. 4. Embedded document