Neuroplasticity: How to rewire your brain

Scientists once thought that the brain was locked in place after puberty. But new technology shows that our brain continues to rewire itself and never stops changing as we age.

Kubernetes architecture

Main components of K8s

Master Node

API ServerThe API Server communicates with all the components within the cluster.
Key-Value Store (etcd)A light-weight distributed key-value store used to accumulate all cluster data.
ControllerUses the API Server to monitor the state of the cluster. It tries to move the actual state of the cluster to match the desired state from your manifest file.
SchedulerSchedules newly created pods onto worker nodes. Always selects nodes with the least traffic to balance the workload.

Worker Node

Worker nodes are the machines where the containerized workloads and storage volumes are deployed.

There are multiple instances of Worker Nodes, each performing their assigned tasks.

KubeletA daemon that runs on each node and responds to the master’s requests to create, destroy, and monitor pods on that machine.
Container Runtimecontainer runtime retrieves images from a container image registry and starts and stops containers. This is usually a 3rd party software or plugin, such as Docker.
Kube-proxyA network proxy that maintains network communication to your Pods from within or from outside the cluster.
Add-ons (DNS, Web UI..)Additional features you can add to your cluster to extend certain functionalities.
Podpod is the smallest element of scheduling in Kubernetes. It represents a ‘wrapper’ for the container with the application code. If you need to scale your app within a Kubernetes cluster, you can only do so by adding or removing pods. A node can host multiple pods.

SQL to MongoDB Mapping

Terminology and Concepts

SQL Terms/ConceptsMongoDB Terms/Concepts
rowdocument or BSON document
table joins$lookup, embedded documents
primary keySpecify any unique column or column combination as primary key.primary keyIn MongoDB, the primary key is automatically set to the _id field.
aggregation (e.g. group by)aggregation pipelineSee the SQL to Aggregation Mapping Chart.
SELECT INTO NEW_TABLE$outSee the SQL to Aggregation Mapping Chart.
MERGE INTO TABLE$merge (Available starting in MongoDB 4.2)See the SQL to Aggregation Mapping Chart.
UNION ALL$unionWith (Available starting in MongoDB 4.4)


MongoDB MySQL Oracle Informix DB2

Database Server mongod  mysqld oracle IDS DB2 Server

Database Client mongo  mysql sqlplus DB-Access DB2 Client

Create, Alter and Drop



Update Records

Delete Records

MongoDB Collection

You can create a collection (Table) using the command line or GUI.

Here we hit the first error.

As you can see in the above error. You can’t create under the ‘admin’.

You can insert the data into collection (table) from json or csv etc.

Never to miss some important points here.

If you note it carefully from the below screenshot, you will notice that a collection(table) can be export (as you can see the arrow below 1. marked red) and even can import file or document. As already said you can import the data from csv or JSON too.

Below screenshot reminded me about the MySQL database. That also got the same options.