mongodb

commands

backup MongoDB data

• running on the same machine and on the default port of 27017
• backup data is dumped on dump directory.

mongodump -u <username> -p <password> -h <hostname> --port <port> -d <database> --out <outputfile>

restore MongoDB data

• restore MongoDB data from specified directory

mongorestore -u <username> -p <password> -h <hostname> --port <port> -d <database> <restore data directory path>

start mongod daemon with specified configuration file

mongod --config /usr/local/etc/mongod.conf

execute mongodb command from javascript file

mongo <database host ip or fqdn>/<database name> <javascript file path>

add a new field all documents in a collection

• https://glassonionblog.wordpress.com/2012/03/19/mongodb-adding-a-new-field-all-documents-in-a-collection/

db.<collection name>.update({},{ '$set': {"<field.field": ""} }, false, true)

find minimum value from nested object

document example (sample collection)

{
  "_id": ObjectId("xxxxxxxxxx"),
  "pair": {
    "x": 12,
    "y": 34
  }
}
{
...
}

find minimum value of x

db.sample.aggregate([
{
  $group: {
    _id: {},
    minX: {
      $min: "$pair.x"
    }
  }
}
])

find minimum value of x and minimum value of y

db.sample.aggregate([{
  $group: {
    _id: {},
    minX: {
      $min: "$pair.x"
    },
    minY: {
      $min: "$pair.y"
    }
  }
}])

GridFS

remove file by name

mongofiles -v -d <database name> delete <filename>