MongoDB shell cheat sheet, to Start Practicing the commands. Go to the mongo db bin folder and, If mongo db server is installed on local system, just type monogo and we will be connected. If using a database-as-a-service (daas)instance wanting to connect using mongo shell. MongoDB is a cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas. MongoDB Cheat Sheet tries to provide a basic reference for beginner and advanced developers, lower the entry barrier for newcomers, and help veterans refresh the old tricks. Post a comment on Quick Access To Mongodb Commands Cheat Sheet If you have a TypeKey or TypePad account, please Sign In You are currently signed in as (nobody). How to Write Shell Script in Linux/Unix. Shell Scripts are written using text editors. On your Linux system, open a text editor program, open a new file to begin typing a shell script or shell programming, then give the shell permission to execute your shell script and put your script at the location from where the shell can find it.

• Mongodb Shell Commands
• Mongodb Shell Cheat Sheet 2020
• Cheat Sheet Terraria
• Mongodb Shell Cheat Sheet 2019
• Mongodb Shell Js
• Mongodb Cheat Sheet Pdf
• Pymongo Cheat Sheet

There are many GUI tools to connect to MongoDB databases and browse but sometimes you need to get to the command line. That moment when something has gone wrong on the database server, and you need to SSH 4-levels deep in order to debug a problem with a database can leave you stuck.

In this cheat sheet you can get a quick refresher on:

• Starting the mongo shell

• Navigating around Mongo

• Working with a collection

• Changing groups of documents

• Working with individual documents and Indexes

• Dangers to avoid

Created for personal use by Red Hat’s own Cian Clarke, we’ve cleaned it up a bit for your use.

There are many GUI tools to connect to MongoDB databases and browse but sometimes you need to get to the command line. That moment when something has gone wrong on the database server, and you need to SSH 4-levels deep in order to debug a problem with a database can leave you stuck.

In this cheat sheet you can get a quick refresher on:

• Starting the mongo shell

• Navigating around Mongo

• Working with a collection

• Changing groups of documents

• Working with individual documents and Indexes

• Dangers to avoid

Created for personal use by Red Hat’s own Cian Clarke, we’ve cleaned it up a bit for your use.

MongoDB is a popular NoSQL database that allows unauthenticated access by default.

Regardless of the user’s authentication database, Mongo always stores user information in admin.

Mongodb Shell Commands

MongoDB stores all user information, including name, password, and the user’s authentication database, in the system.users collection in the admin database.

See centralized-user-data and system-users-collection.

When you create a user and grant that user access to a single database (aka their authentication database) then that information can only be stored in the admin database.

So, it’s not really a question of “best practice”; storing user details in admin is MongoDB’s choice, as implemented by their user management commands.

Update in response to this comment:

Ok, so the users are always located in the admin db, but I may also add “duplicates” to the other dbs? Maybe the question should be whether there any advantage in adding users to the other “non admin” dbs?

Mongodb Shell Cheat Sheet 2020

If you intend to have a single user with access to multiple databases then create a single user with roles in each of those databases rather than creating that user multiple times i.e. once in each of those databases. For example:

Create initial admin user

Sharded Cluster with enforced authentication

Create:

• a cluster-wide admin user
• a replica set specific admin user

Cluster-wide Admin

Replica Set Admin (a.k.a shard local)

Enable authentication in the mongos configuration

Connect to all replica set member nodes

Authenticate and check that the admin users exist

Log in

Rename collections

Copy Collection

Check replication set status

Backup/Restore

Documents

Admin commands

TLS 1.2 for Mongo Routers

To protect your application’s database connection enable TLS on the mongo routers as follows. Note that your mongo driver configuration needs to trust the CA certificate and enable transport encryption with ssl=true.

Rolling Update/Cluster Patching

Maintenance (startup in reverse order):

Replication Concept

1. write operations go to the primary node
2. all changes are recorded into operations log
3. asynchronous replication to secondary
4. secondaries copy the primary oplog
5. secondary can use sync source secondary*

• automatic failover on primary failure

*settings.chainingAllowed (true by default)

Replica set oplog

Cheat Sheet Terraria

• special capped collection that keeps a rolling record of all operations that modify the data stored in the databases
• idempotent

• default oplog size (for Unix and Windows systems):

  Storage Engine	Default Oplog Size	Lower Bound	Upper Bound
  In-memory	5% of physical memory	50MB	50GB
  WiredTiger	5% of free disk space	990MB	50GB
  MMAPv1	5% of free disk space	990MB	50GB

Deployment

• start each server with config options for replSet
  /usr/bin/mongod --replSet 'myRepl'
• initiate the replica set on one node - rs.initialize()
• verify the configuration - rs.conf()
• add the rest of the nodes - rs.add() on the primary node
  rs.add('node2:27017') , rs.add('node3:27017')
• check the status of the replica set - rs.status()

Sharding

Components

• shard/replica set - subset of the sharded data
• config servers - metadata and config settings
• mongos - query router, cluster interface
  sh.addShard('shardName')

Shards

• contains subset of sharded data
• replica set for redundancy and HA with odd number of voting members
• primary shard
• don’t shard collections if dataset fits into single server
• –shardsvr in config file (port 27018)
• every xxx has a primary shard per database
• all non-shared collections will reside on primary shard

Shard keys (and limitations)

• shard keys are immutable with max size of 512 bytes (can not be updated/changed)
• must be ascending indexed key or indexed compound keys that exists in every document in the collection
• cannot be multikey index, a text index or a geospatial index
• update operations that affect a single document must include the shard key or the _id field
• no option for sharding if unique indexes on other fields exist
• no option for second unique index if the shard key is unique index
• ranged sharding may not distribute the data evenly
• hashed sharding distributes the data randomly

Mongodb Shell Cheat Sheet 2019

Config servers

• config servers as replica set (only 3.4)
• stores the metadata for sharded cluster in config database
• authentication configuration information in admin database
• holds balancer on Primary node (>= 3.4)
• –configsvr in config file (port 27019)

mongos

Mongodb Shell Js

• caching metadata from config servers
• routes queries to shards
• no persistent state
• updates cache on metadata changes
• holds balancer (mongodb <= 3.2)
• mongos version 3.4 can not connect to earlier mongod version

Sharding collection

Mongodb Cheat Sheet Pdf

Pymongo Cheat Sheet