junzis · April 20, 2016 13:43
diff --git a/_mongodb_scripts b/_mongodb_scripts
 # a set of useful scripts for mongodb

 - batch deleting collections
 - extract subset using fast aggregation method
 - export query to csv (quick and dirty)
diff --git a/mongodb_batch_delete_collection b/mongodb_batch_delete_collection
 var collectionNames = db.getCollectionNames();

 for(var i = 0, len = collectionNames.length; i < len ; i++){
  var collectionName = collectionNames[i];
  if(collectionName.indexOf('NAMESTARTS_') == 0){
    db[collectionName].drop()
  }
 }
diff --git a/mongodb_dump_collection b/mongodb_dump_collection
 mongodump --db database_name --collection collection_name --out - | gzip > dump_file_name.gz
diff --git a/mongodb_export_to_csv b/mongodb_export_to_csv
 mongoexport -d DB -c COLL --type=csv --out file_name.csv --fields f1,f2,f3
diff --git a/mongodb_extract_subset b/mongodb_extract_subset
 db.getCollection('FULL_SET').aggregate([{ $match:{ FIELD:"VALUE"} }, { $out: "SUB_SET" }]);
diff --git a/mongodb_get_last_record b/mongodb_get_last_record
 db.collection.find().limit(1).sort({$natural:-1})
diff --git a/mongodb_mapreduce_histogram b/mongodb_mapreduce_histogram
 db.COLLECTION_NAME.mapReduce(
    function(){
        var lat = Math.floor(this["loc"]["lat"]);
        var lon = Math.floor(this["loc"]["lng"]);
        var key = lat + "_" + lon;
        emit(key, {count: 1})
    }, 
    function(state, values){
        var result = {count: 0};
        values.forEach(function(value) {
            result.count += value.count;
        });
        return result;
    }, 
    {out: "histogram"}
 );
diff --git a/mongodb_move_collection b/mongodb_move_collection
 use admin

 db.runCommand({renameCollection:"sourcedb.mycol",to:"targetdb.mycol"})
diff --git a/mongodb_query_to_csv b/mongodb_query_to_csv
 mongoexport -d DBNAME -c COLLNAME --query "{'FIELD':'VLAUE'}" --type=csv --fields F1,F2,F3 --out out.csv
	# a set of useful scripts for mongodb

	- batch deleting collections
	- extract subset using fast aggregation method
	- export query to csv (quick and dirty)
	var collectionNames = db.getCollectionNames();

	for(var i = 0, len = collectionNames.length; i < len ; i++){
	var collectionName = collectionNames[i];
	if(collectionName.indexOf('NAMESTARTS_') == 0){
	db[collectionName].drop()
	}
	}
	db.COLLECTION_NAME.mapReduce(
	function(){
	var lat = Math.floor(this["loc"]["lat"]);
	var lon = Math.floor(this["loc"]["lng"]);
	var key = lat + "_" + lon;
	emit(key, {count: 1})
	},
	function(state, values){
	var result = {count: 0};
	values.forEach(function(value) {
	result.count += value.count;
	});
	return result;
	},
	{out: "histogram"}
	);
	use admin

	db.runCommand({renameCollection:"sourcedb.mycol",to:"targetdb.mycol"})