#1.1 MongoDB basics

1. Installing on archLinux: Install mongodb from official repositories:

# pacman -S mongodb



2. Edit some options of the configuration file in /etc/mongodb.conf

standard file:
# See http://www.mongodb.org/display/DOCS/File+Based+Configuration for format details
# Run mongod --help to see a list of options

bind_ip = 127.0.0.1
quiet = true
dbpath = /var/lib/mongodb
logpath = /var/log/mongodb/mongod.log
logappend = true

edited file:
storage:
   dbPath: /mongodb/data/db
   directoryPerDB: true
systemLog:
   destination: file
   path: "/mongodb/log/mongo.log"
   logAppend: true
   verbosity: 3
   quiet: true

net:

   http:

      RESTInterfaceEnabled: true

Note 1: the dbpath and log path refer to /mongodb/data/db and /mongodb/log, respectively. These directories must be created and chown to user mongodb and group daemon;

Note 2: the log path points to a file mongo.log that must be created: touch /mongodb/log/mongo.log;

Note 3: by enabling the REST API, the HTTP interface is also enabled and, as a result, can increase network exposure.

3. Enable/Start the mongodb.service daemon:

# systemctl enable mongodb.service
# systemctl start mongodb.service

4. Basic configuration for non-daemon execution:

# mongod --directoryperdb --dbpath /mongodb/data/db --logpath /mongodb/log/mongo.log --logappend --rest

parameters description:

--directoryperdb -> each database will be stored in a separate directory;

--dbpath -> directory for datafiles - defaults to /data/db;

--logpath -> log file to send write to instead of stdout - has to be a file, not directory;

--logappend -> append to logpath instead of over-writing;

--rest -> turn on simple rest api;

5. To access the Database shell:

# mongo

6. Basic commands for beginners:

- list all existing databases

# show dbs

- create and switch to a new database

# use <db>

- check the current database

# db

- create a new user for the current database
# db.createUser({
user:"<name>",
pwd:"<pwd>",
roles:["readWrite", "dbAdmin"]
});

- create a new collection
# db.createCollection('<collection_name>');

- list all collections for the current database
# show collections

- insert a document (record) in the collection
# db.<collection_name>.insert({
first_name: "John",
last_name: "Doe"
});

- list documents in the collection

# db.<collection_name>.find()

or

# db.<collection_name>.find().pretty()

- update a document / set (add) a new field
# db.<collection_name>.update({first_name:"John"},{first_name: "John", last_name: "Doe", gender:"male"});
or
# db.<collection_name>.update({first_name:"John"},{$set:{gender:"male", age: 45}});

- increment function
# db.<collection_name>.update({first_name:"John"},{$inc:{age: 5}});

- unset (remove) a field in the document
# db.<collection_name>.update({first_name:"John"},{$unset:{age:1}});

- upsert option (update if found, or insert if not found)
# db.<collection_name>.update({first_name:"Mary"},{first_name: "Mary", last_name: "Poppings", gender:"female"},{upsert: true});

- rename an attribute (field)

# db.<collection_name>.update({first_name:"Mary"},{$rename:{"gender":"sex"}});

- remove a document (record)

# db.<collection_name>.remove({first_name:"Mary"})

or

# db.<collection_name>.remove({first_name:"Mary"},{justOne: true})

- search a specific document (record)

# db.<collection_name>.find({first_name: "John"})

or

# db.<collection_name>.find({$or:[{first_name: "John"},{first_name: "Mary"}]})

- search with options "lower than" or "greater than"

# db.<collection_name>.find({age:{$lt:40}})

other options: lt/lte/gt/gte

- sort documents

# db.<collection_name>.find().sort({first_name:1})

options: 1 (ascending), -1 (descending)

- count documents

# db.<collection_name>.find().count()

- limit the record count (first x documents)

# db.<collection_name>.find().limit(x)

- using forEarch and custom output

# db.<collection_name>.find().forEach(function(doc){print("Customer Name: "+doc.first_name)})

References:

- https://wiki.archlinux.org/index.php/MongoDB

- https://docs.mongodb.com/manual/reference/configuration-options/
- https://youtu.be/pWbMrx5rVBE