mongodb query performance

Mongodb deduplication, aggregation, query explanation, mongodb Aggregation I recently learned about mongodb and some people understand it: 1. deduplication Repeated template. getCollection (collectionName). distinct () returns the list set, which is the result after deduplication. 2. Aggregation Aggregation aggre

performance. There is no bottleneck in MongoDB read performance in the test due to data volume, or YCSB bottlenecks.7. Conclusion1.Mongodb reading performance is very high, suitable for rereading the scene.2. By adding shards, you can greatly increase the write

": "Wangwu", "Age" : $ > Db.stud Ent.find (). Skip (3). Limit (3) "_id": 4, "name": "Zhaoliu", "Age": "_id": 5, "name": " Qianliu "," Age ": " _id ": 6," name ":" Sunba "," Age ": + > Db.student.find (). SK IP (6). Limit (3) "_id": 7, "name": 7, "Age": 70} Db. Collection name. Find (). Sort ({key: number})A number of 1 means ascending, and a number of 2 means descending > Db.student.find (). Sort ({age:1}) { "_id": 1, "name": "Zhangsan", "age": +, "sex": 1 } { "_id": 2, "name": "Lisi", "age": 2

this method, we can see from the test results that the overall Write Performance is higher than that of MySQL and handlersocket, which is a trade-off, it depends on whether the specific business can accept such high performance in exchange for data reliability, some businesses may be acceptable, such as feed. 2. CPU usageFrom the query results, we can see that

Tags: mongodb regular expression PerlMongoDB in Find query using Perl-compatible regular expressionsPerl Express Description: Http://www.chinaunix.net/old_jh/25/159388.htmlExample:>db.post.find () { "_id" :objectid ("54a530c3ff0df3732bac1681"), "id" :2, "name" : "Joe", "age" :30, "Sex" :1, " School ":" Marry "}{" _id ":objectid (" 54a530c3ff0df3732bac1680 ")," id ":1," name ":" Joe "," Age ":30, "Comments"

Label:1. MongoDB starts from a configuration file Create configuration file:/usr/local/mongodb/etc/mongodb.conf The contents of the configuration file are: #Directory and relavent set DBPath =/var/mongodb/data logpath =/var/mongodb/logs/log.log profile=2 slowms=100 #repairpath =/var/

. TT actually has a memory buffer, but it is much smaller than the former.The above tests are not complete, but they are just the beginning. For example, there is no small data test (using numbers as the key, 100 bytes Value), and there is no big data test (about 20 kB ); performance in hit situations is not tested; concurrent read/write performance is not tested, it is reported that

[MongoDB] The high query operation of MongoDB (2), mongodboperation In the last blog, there are three query condition to be described. In the blog, we will continue to what we have leaned in the last blog.1 $ mod '$ Mod' operation is able to make us to do simple mod operation, but is no need to use where sentence. \2.

Tags: style blog http color io strong SP data onMONGOBD's query is plainly a find () method. But it's still a little complicated. Come on(1) Query all data: DB. Collection name. Find (); There's nothing to say.(2) Query the first data: DB. Set name. FindOne (); There's nothing to say.(3) Condition query: DB. Set name.

. (11) In addition to prefix-style queries, regular expression queries cannot use indexes and execute longer than most selectors, and they should be used sparingly. (12) In an aggregation operation, $match the number of documents to be processed by the $ group operator in front of the $ group, by $match predecessor. (13) Modifying a document by using an operator typically provides better performance because it does not require a round-trip se

Function name Regexobjsubobjkeyfunction codefunction(proto,value) {varMatch=false; varReg =NewREGEXP ('. * ' +value); Print (Json.stringify ( This. obj)); Print ( This[' Arr_ ' +Proto]); for(varKeyinch This. obj[' Arr_ ' +Proto]) {print (key); if(key!= ' count ' key!= ' isgame ') {Match=reg.test (key); if(match) {return true; } } } return false;}Query DemoStreamlineDb.test.find ({$where: "Regexobjsubobjkey (' qq ', ' 1234567 ')"}

you can't do it. MongoDB leads the nosql movement. Note that the most important thing we oppose is the SQL methodology. You can only get disappointed when using mangodb using SQL. Think about MongoDB's design philosophy: docization. _ Id is the file name, And MongoDB is a file system. Full-text search? Don't bother. Use a file name to find a file. A file name corresponds to a file, and you will never be di

of setting method and level, one is by adding –slowms boot parameter configuration. The second is to invoke Db.setprofilinglevel with the second argument: Db.setprofilinglevel (level, SLOWMS) 2. Query Profiling Records Unlike MySQL's slow query log, the MongoDB profile record is directly present in the system DB, and the record location is System.

MongoDB entry-add, delete, modify, and query-mongodb entry-add, delete Mongodb has been successfully started in the previous blog: continue. Open another cmd and enter the [mongo] command to open the shell, that is, the mongodb client. The "test" database is connected by de

turn on the Profiling function To optimize for slow queries: MongoDB can monitor data through profile to optimize it.To see whether the profile function is currently open with commandsDb.getprofilinglevel () returns level with a value of 0|1|2, meaning: 0 for off, 1 for slow command, 2 for allDb.setprofilinglevel (level); #level等级, value ibid.At level 1, the slow command defaults to 100ms and changes to Db.setprofilinglevel (LEVEL,SLOWMS) such as Db.

Implementation tutorial of MongoDB set field matching query method, mongodb Field MongoDB is a distributed file storage-based database. This article describes how to perform matching queries on the fields integrated in MongoDB records.1. Create a Test Database use testdbdb.

Tags: wan theory large number of connections coded pad memory alt modeThe performance test of MONGODB billion data volume was carried out, and the following items were tested:(All inserts are single-threaded and all reads are multithreaded) 1) Normal insertion performance (the inserted data is about 1KB per piece) 2) Bulk Insert

Similar to hibernaterepository, by inheriting the mongorepository interface, we can easily add, delete, modify, and query an object. To use the repository function, we must first inherit the mongorepository Example: Public interface personrepository extends mongorepository However, mongorepository only implements the most basic addition, deletion, modification, and query functions. To add additional

Introduction to MongoDB and addition, deletion, modification, and query I. Introduction MongoDB is written in C ++ and is an open source database system based on distributed file storage. MongoDB is designed to provide scalable, high-performance data storage solutions for WE

a winning design method, you may still be able to write it slowly. Because MongoDB does not have good guidance and constraints in interface design, if you do not pay attention to it, you can still use it very slowly. The first problem: the key-value database may have a lot of keys. That's right, but it's a big mistake for MongoDB. MongoDB index costs a lot, t