Mongo 学习笔记

2018-03-07 posted in [技术]

1 - BASE OPERATION

Insert 1

db.people.insert({name:’zhaoyun’, ‘age’: 37});

Insert 2

var person = {name:’purong’, ‘age’:38};
db.people.insert(person);

Insert 3

for (var i=0; i<20; i++) { db.people.insert({name:'user_' + i, age: 30 + i}); }

Remove

db.people.remove({‘name’:’not-exists’});

Remove All

db.people.remove({});

Find All

db.people.find()

Find 1

db.people.find({‘name’:’zhaoyun’});

Find 2

db.people.find({‘name’: {$lt: 38}); // $lt $gt $lge $gte $ne

Find 3

db.people.find({’name’:’zhaoyun’, age:{$lt:38}});

Find 4

db.people.find({$or:[{’name’:’zhaoyun'},{‘age’:{$gt:37}}]});
db.people.find({‘age’: {$in:[37, 38]}}); // $nin

Find 5

db.people.find({‘name’:/.*o.*/});

Find 6

db.people.find({‘name’:/^zh/, ‘name’:/un$/});

Find 7

db.people.find({$where:function() { return this.name==‘zhaoyun'}});

Update 1

db.people.update({’name’: ‘zhaoyun'}, {’name’:’zhaoyun’, ‘age’:37});

Update 2

db.people.update({’name’:’zhaoyun’}, {$inc:{‘age’:1}}); // age += 1

Update 3

db.people.update({’name’:’zhaoyun'}, {$set:{‘age’: 28}});

Update 4: Upsert

// if found, update ‘age’, otherwise insert new document
db.people.update({'name':'purong'},{$set:{'age':38}}, true);

Update 5: Update all

// As default, mongo update will effect on first match document,
// set (true) value for the 4th parameters of update statement to voice: I need update all.

2 - ADVANCE

Count 1

db.people.count();

Count 2

db.people.count({age:{$lt: 38}});

Distinct

db.people.distinct(‘age'); // [ 37, 38 ]

Group 1

db.people.group({key:{age:true}, initial:{num:0}, $reduce:function(doc,prev){prev.num++}});
db.people.group({key: {age:true}, initial: {person:[]}, $reduce:function(cur,prev){prev.person.push(cur.name);}})

Group 2

db.people.group({ key:{age:true}, initial:{ users:[] }, $reduce:function(doc, prev) { prev.users.push(doc.name); },condition:{age:{$lt:35}} });

Group 3

db.people.group({ key:{age:true}, initial:{ users:[] }, $reduce:function(doc, prev) { prev.users.push(doc.name); }, finalize:function(out) { out.xx = out.users.length }, condition:{age:{$lt:35}} });

MapReduce

var map = function() { emit(this.age, {count:1}); }
var reduce = function(key, value) { var result = {count:0}; for (var i=0; i<value.length; i++) { result.count += value[i].count; } return result; }
db.people.mapReduce(map, reduce, { out: 'collection1'})
db.collection1.find()

Cursor

var list = db.people.find();
list.forEach(x => { print(x.name); })

Compose Query

var single=db.people.find().sort({'name',1}).skip(2).limit(2);

Query & Index

db.people.remove({});
for (var i=0; i<100000; i++) { db.people.insert({ name: 'zhaoyun_' + parseInt(i * Math.random()), age:i }); }

db.people.find({name:'zhaoyun_20000'}).explain('executionStats’) // see time used 'executionTimeMillis'

db.people.ensureIndex({ name: 1 }) // 1: Ascending, -1: Descending
db.people.find({name:'zhaoyun_20000'}).explain('executionStats’) // see time used 'executionTimeMillis'

Unique Index

db.person.ensureIndex({"name":1},{"unique":true}) // duplicate value can’t be insert or update

Compose Index

db.people.ensureIndex({ name: 1, age: -1 }) // 1: Ascending, -1: Descending

List & Drop Indexes

db.people.getIndexes();
db.people.dropIndex('name_1');

Master / Slave deploy

// create difference folders for db-master / db-slave
mkdir dbmaster dbslave

// startup 2 mongodb server on difference port
mongod —dbpath=./dbmaster —port=27017 —master &
mongod —dbpath=./dbslave —port=20178 —slave —source=127.0.0.1:27017 &

// connect to master, insert some data
mongo 127.0.0.1:27017
use test
db.people.insert({name:'zhaoyun', age:37});

// connect to slave, see data from master
mongo 127.0.0.1:27018
db.slaveOk(); // as default, slave only do synchronize, can’t read & write
use test
db.people.find()