Tag: find

MongoDB is a NoSQL type of database.

Installation on Windows is rather simple just follow the prompts. Just download from here. You can follow the installation instructions from here if you so choose. It has a max document size of 16MB but you can see all base configurations from here. Once you install MongoDB you will have to start the server. Run C:\Program Files\MongoDB\Server\3.2\bin\mongod.exe. Then you can run C:\Program Files\MongoDB\Server\3.2\bin\mongo.exe to start querying the data.

MongoDB is a document db. Adhoc querying is easy if the data you are querying is within the 16MB max size. There is no tables in MongoDb they are called Collections instead. They are used to store bson documents. Which are basically json. Querying data is fast I have found. It uses the map reduce context to querying data. If you are not familiar with map reduce it’s basically just JavaScript.

I will have more later as I test more and more.

I have done some testing and can give you some basic code below.

Show All Collections:

 show collections

 

See All Databases:

 show dbs

 

Drop A Collection:

 db.COLLECTIONNAME.drop()

 

Drop All Collections:

 db.getCollectionNames().forEach(function(c) { if (c.indexOf("system.") == -1) db[c].drop(); })

 

Create A Collection:

 db.createCollection("logs", {autoIndexId: true})

 

Create An Index:

 db.logs.createIndex( { KEY: VALUE } )

 

MapReduce:

 db.COLLECTION.mapReduce(function(){
      var key = WHATEVER;
      var value = WHATEVER;

      emit(key, value);
},
function(key, values) {
      var output = {
            KEY: VALUE
      };
      return output;
}, {out: {inline: 1}})

 

Find matching element:
The .pretty() displays the json pretty.

 db.COLLECTIONNAME.find({ "KEY.SUBKEY.ARRAYINDEX" : VALUE }).pretty()

 

Find record that match in using greater and less than or equal to and display the id field associated.

 db.COLLECTIONNAME.find({ "KEY" : {$elemMatch: { $elemMatch: { $gt: 0.0005, $lte: 0.0005862095 } } } }, { id: "_id"  }).pretty()

 

Find record using IN and returning id field.

 db.COLLECTIONNAME.find({ "KEY" : { $in: [ 123,456 ] } }, { id: "_id" }).pretty()

 

You can loop through data and insert it into a new collection

 db.COLLECTIONNAME.find({ "KEY.SUBKEY.ARRAYINDEX" : 0 }).forEach(function(obj){ db.NEWCOLLECTION.insert(obj) })