BASIC MONGO SHELL COMMANDS

Start mongodb. cd /home/mathew/mongodb-linux-x86_64-2.0.6/bin mongod --dbpath ~/temp/mongodata/

Start shell. mongo use contributionsdb; db.contribution.count();

MONGO SHELL COMMANDS

show dbs (lists all the current databases).
use <databasename> (database name I used is contributionsdb).
show collections (collection name I use is contribution).
db.contribution.findOne() (finds one record and displays it).
db.contribution.find({candNm:”name here”}) 
db.contribution.getIndexes() (returns all the current index names).
db.contribution.dropIndex({candNm:1}) (drop existing index).
db.contribution.ensureIndex({candNm:1}) (create index).
db.contribution.ensureIndex({contbrEmployer:1}) (create index).
db.contribution.count() (get count of records in the collection).
db.contribution.remove() (removes the collection).

LOADING DATA

Use JAVA or your fav language to load the data OR use the simple approach... mongoimport --host localhost --db contributionsdb --collection contribution --type csv --file P00000001-ALL.csv --headerline --upsert

RUN MAP REDUCE : FIND MAX AND MIN CONTRIBUTION AMOUNTS PER CANDIDATE

map = function() {
  if ( this.contbReceiptAmt > 0 ) {
     var x = { amt: this.contbReceiptAmt, candNm: this.candNm, contbrNm: this.contbrNm, contbrEmployer: this.contbrEmployer, _id: this._id };
     emit(this.candNm, {min:x, max: x} );
  }
};

reduce = function (key, values) {
    var res = values[0];
    for ( var i=1; i<values.length; i++ ) {
        if ( values[i].min.amt < res.min.amt ) 
           res.min = values[i].min;
        if ( values[i].max.amt > res.max.amt ) 
           res.max = values[i].max;
    }
    return res;
};

db.contribution.mapReduce( map , reduce , { out : { inline : true } } );

RUN MAP REDUCE : TRANSACTION COUNT, TOTAL DOLLARS CONTRIBUTED BY CANDIDATE

map = function() {
    emit( this.candNm, {count: 1, candNm: this.candNm, amt: this.contbReceiptAmt} );
};


reduce = function(key, values) {
    var result = {count: 0, amt: 0, candNm:""};
    values.forEach(function(value) {
      result.count += value.count;
      result.amt += value.amt;
      result.candNm = value.candNm;
    });
    return result;
};
db.contribution.mapReduce( map , reduce , { out : { inline : true } } );

RUN MAP REDUCE : FIND MAX AND MIN CONTRIBUTION AMOUNTS FROM A Company

function isNumber (o) {
  return ! isNaN (o-0) && o != null;
}

map = function() {
  if ( this.contbrEmployer == 'COMPANYNAME' && isNumber(this.contbReceiptAmt)) {
     emit(this.contbrEmployer, { count:1, amt: this.contbReceiptAmt, contbrNm: this.contbrNm } );
  }
};

reduce = function (key, values) {
    var result = {count:0, amt:0};
    values.forEach(function(value) {
      result.count += value.count;
      result.amt += value.amt;
    });
    return result;
};

db.contribution.mapReduce( map , reduce , { out : { inline : true } } );

URL FOR THE REST CALLS

cd /home/mathew/git/mongodb_mongoose_nodejs_express

node basicnodejshello.js (http://localhost:3000/) node basicexpresshello.js (http://localhost:3000/mathew)

node plainmongoose.js (output sent to console)

http://localhost:3000/candidate/findone/Obama,%20Barack http://localhost:3000/candidate/count/Obama,%20Barack http://localhost:3000/candidate/count/Romney,%20Mitt http://localhost:3000/candidate/findall/McCotter,%20Thaddeus%20G http://localhost:3000/candidate/findall/Huntsman,%20Jon

References

MapReduce Overview - http://kylebanker.com/blog/2009/12/mongodb-map-reduce-basics/