kinganeng · August 29, 2015 14:25
diff --git a/Using cron to perform incremental Map-Reduce in MongoDB b/Using cron to perform incremental Map-Reduce in MongoDB
 Using cron to perform incremental Map-Reduce in MongoDB
diff --git a/1. init_tags.js b/1. init_tags.js
 //The Map function, simply count tags
 var mapTags = function() {
    if (!this.tags) {
        return;
    }

    for (index in this.tags) {
        emit(this.tags[index], 1);
    }
 };

 //The Reduce function, accumulate the count
 var reduceTags = function(previous, current) {
    var count = 0;

    for (index in current) {
        count += current[index];
    }

    return count;
 }

 var conn = new Mongo();
 var db = conn.getDB("your_db");

 //save the functions
 db.system.js.save(
               { _id: "mapTags",
                 value : mapTags
                   }
                 )

 db.system.js.save(
               { _id: "reduceTags",
                 value : reduceTags
                   }
                 )
 //execute the Map-Reduce, 
 //the results will be stored in the calc_tags collection
 db.yeedd.mapReduce( mapTags,
                    reduceTags,
                    {
                      out: "calc_tags"
                    }
                  )
diff --git a/2. inc_tags.js b/2. inc_tags.js
 //convert ISO data to ObjectId so that it can be compared with ObjectIds in db
 var ISODateToObjectId = function(date){
    // Convert date to hex seconds
    var hexSeconds = Math.floor(date.getTime()/1000).toString(16);

    // Create an ObjectId with the hex timestamp
    var id = ObjectId(hexSeconds + "0000000000000000");

    return id
 }

 var conn = new Mongo();
 var db = conn.getDB("your_db");

 var start = new Date();
 start.setDate(start.getDate()  - 1)

 // The Map and the Reduce functions have been stored into system.js
 // and they can be used in the mapReduce function now 
 db.yeedd.mapReduce( mapTags,
                    reduceTags,
                    {
                         query: { _id: { $gt: ISODateToObjectId(start) } },
                         out: { reduce: "calc_tags" }
                       }
                     );
 }
diff --git a/3. init_tags.sh b/3. init_tags.sh
 # execute javascript file with mongo shell. 
 # please use your own file path and database path instead
 /usr/bin/mongo "localhost:27017/db"  /path/to/init_tags.js
diff --git a/4. inc_tags.sh b/4. inc_tags.sh
 # execute javascript file with mongo shell. 
 # please use your own file path and database path instead
 /usr/bin/mongo "localhost:27017/db"  /path/to/inc_tags.js
diff --git a/5. cron_job b/5. cron_job
 01 0 * * * /path/to/inc_tags_job.sh
	//The Map function, simply count tags
	var mapTags = function() {
	if (!this.tags) {
	return;
	}

	for (index in this.tags) {
	emit(this.tags[index], 1);
	}
	};

	//The Reduce function, accumulate the count
	var reduceTags = function(previous, current) {
	var count = 0;

	for (index in current) {
	count += current[index];
	}

	return count;
	}

	var conn = new Mongo();
	var db = conn.getDB("your_db");

	//save the functions
	db.system.js.save(
	{ _id: "mapTags",
	value : mapTags
	}
	)

	db.system.js.save(
	{ _id: "reduceTags",
	value : reduceTags
	}
	)
	//execute the Map-Reduce,
	//the results will be stored in the calc_tags collection
	db.yeedd.mapReduce( mapTags,
	reduceTags,
	{
	out: "calc_tags"
	}
	)
	//convert ISO data to ObjectId so that it can be compared with ObjectIds in db
	var ISODateToObjectId = function(date){
	// Convert date to hex seconds
	var hexSeconds = Math.floor(date.getTime()/1000).toString(16);

	// Create an ObjectId with the hex timestamp
	var id = ObjectId(hexSeconds + "0000000000000000");

	return id
	}

	var conn = new Mongo();
	var db = conn.getDB("your_db");

	var start = new Date();
	start.setDate(start.getDate() - 1)

	// The Map and the Reduce functions have been stored into system.js
	// and they can be used in the mapReduce function now
	db.yeedd.mapReduce( mapTags,
	reduceTags,
	{
	query: { _id: { $gt: ISODateToObjectId(start) } },
	out: { reduce: "calc_tags" }
	}
	);
	}
	# execute javascript file with mongo shell.
	# please use your own file path and database path instead
	/usr/bin/mongo "localhost:27017/db" /path/to/init_tags.js