Recently I discovered a useful utility called usql while trying to find a better CLI for MySQL. I personally prefer psql PostgreSQL command-line tool so I was trying to find a similar tool for MySQL. During my search for the psql like MySQL CLI I stumbled upon usql – universal command-line interface for SQL database. I like playing with CLI tools as they play a big role in improving the developer experience.
I discovered that there is another popular project in Microsoft world with the same name. It is called U-SQL. U-SQL is the new big data query language of the Azure Data Lake Analytics service.
We are living in a world where every other day we see a new technical innovation. For most of us mere mortal it is not easy to quickly figure out if the technology is worth our time. Making sense of new technical innovations is one of the core aspects of my current role so by taking the pain of writing this series I will help myself as well.
In this post, I will cover Dapr. Dapr stands for distributed application runtime.
What does distributed application runtime means?
These days most of us are developing distributed systems. If you are building an application that uses Microservices architecture then you are building a distributed system.
A distributed system is a collection of autonomous computing elements that appears to its users as a single coherent system.
Distributed application runtime provides you the facilities that you can use to build distributed systems. These facilities include:
State management. Most applications need to talk to a datastore to store state. Common examples like PostgreSQL, Redis, etc.
Pub/sub. For communication between different components and services.
Service to service communication. This also includes retries, circuit breaking.
Observability. To bring visibility into systems.
Secret management. For storing password and keys.
One important thing to note is that these are application level concerns. Distributed application runtime does not concern itself with infrastructure or network level concerns.
The below is the text from Hell Yeah or No book. It gives a good mental model to reason how one live their life. I don’t think one has to entirely in one list or the other. You will be more aligned to one list than the other. Also, I don’t think one is better than the other.
Pursue pleasure, excitement, and novelty
Focus on immediate gratification
Especially appreciate life, nature, and the people around them
Are playful, impulsive, and sensual
Avoid anything boring, difficult, or repetitive
Get fully immersed in the moment and lose track of time
Are more likely to use drugs and alcohol
Are better at helping others than helping themselves
Are driven with self-discipline because they vividly see their future goals
Tend to live in their minds, picturing other selves, scenarios, and possible futures
Especially love their work
Exercise, invest, and go for preventative health exams
Are better at helping themselves, but worse at helping others
Are more likely to be successful in their careers, but often at the expense of personal relationships, which require a present focus
Last week I had to create a visualisation for organization entity chart. The complexity was that an entity can be created by merging of two entities. So, I was looking for a solution that gives the flexibility to have two parent nodes. I started with D3.js but quickly figured out that tree charts in D3.js can’t have two parent nodes. After a lot of googling and trying many different libraries I decided to create that using Graphviz. The only problem was that I wanted to do it on the client side.
Below is the chart that I wanted to create. As you can see below – Dummy Org ABC Limited has two parents Dummy Org India Ltd and Dummy Org East Africa DMCC. Similarly, Dummy Org Devs Project has two parents Dummy Org Infrastructure Limited and Dummy Org Infrastructure & Dummy Org Project
I am doing software development for the last 15 years. Since I heard the term “Full Stack Developer” few years back I had a strong dislike for this term. To most people full stack developer is someone who can write frontend code, build backend APIs, and deploy applications to cloud. They can code in multiple programming languages(JS/Typescript, Golang/Java/C#/Python), knows enough to design and store data in either relational and NoSQL databases, follow DevOps practices (CI, Configuration management, etc.), knows about multiple architecture styles – Microservices, Monolithic, Serverless, and can at least deploy to one public cloud. Along with all this they also know and practice automation testing and can write clean, maintainable code.
The 1% rule states that within an internet community only 1% of the users of a website add content, while the other 99% of the participants only lurk. Another variant of this law is 90-9-1 rule which states that in a collaborative website such as a wiki, 90% of the participants of a community only consume content, 9% of the participants change or update content, and 1% of the participants add content. – Link
The broken windows theory is a criminological theory that states that visible signs of crime, anti-social behavior, and civil disorder create an urban environment that encourages further crime and disorder, including serious crimes. Social psychologists and police officers tend to agree that if a window in a building is broken and is left unrepaired, all the rest of the windows will soon be broken. This is as true in nice neighborhoods as in rundown ones. This theory has been applied to software development, suggesting that poor quality code (or Technical Debt) can lead to a perception that efforts to improve quality may be ignored or undervalued, thus leading to further poor quality code. This effect cascades leading to a great decrease in quality over time. – Link
Today, I was working on an application that uses Microservices based architecture. Each Microservice had its own schema and they talk to each other using their published contracts.
We wanted to keep database migration script with each Microservice rather than keeping a common module to manage database Migrations. We might later migrate to common module for database migration but we want to start by keeping schema for each Microservice separate.
Since last couple of years I have not learnt any new programming language so this week I decided to change that. I decided to learn Swift programming language.
Swift is a modern, multi-paradigm, compiled, statically typed, safe, open-source programming language by Apple. Most developers use it to build apps for Apple platforms – macOS, iOS, watchOS, tvOS and beyond.
I don’t build Apple apps for living. For most of software engineering life I have built web applications and backend services. So,the best way for me to learn a new language is to build a web application using it. In this tutorial series I will be building a web application from scratch using Swift. We will be using Vapor web framework. It is the most used web framework for Swift. Vapor is non-blocking and event-driven built on top of Apple’s SwiftNIO.
Below is the list of management and leadership lessons that I find useful. I collected them from various books and articles I read in the last few years. It is a work in progress so I will keep updating this list as I learn more on this subject.
The greatest leader is not necessarily the one who does the greatest things. He is the one that gets the people to do the greatest things.
Today, I was helping a team that was getting a database deadlock in their Java Spring Boot application using Microsoft SQL Server. The stacktrace of the error was as shown below.
Exception is org.springframework.dao.CannotAcquireLockException: could not execute query; SQL ; nested exception is org.hibernate.exception.LockAcquisitionException: could not execute query] with root cause
com.microsoft.sqlserver.jdbc.SQLServerException: Transaction (Process ID 132) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.
The database deadlock was caused when user uploads a file that was being written to the database. While the file was being uploaded user navigated to another page where data from the same table was queried.
When we debugged SQL Server traces we discovered that row-level lock was escalated to table lock. This was causing SQL Server to stop other transactions from accessing the table.
To solve this issue we enabled READ_COMMITTED_SNAPSHOT option for the database so that it uses READ_COMMITTED with row versioning isolation strategy. The default database isolation level in SQL Server is READ_COMMITTED which means a query in the current transaction cannot read data modified by another transaction that has not yet committed, thus preventing dirty reads. The isolation level uses shared locking or row versioning to prevent dirty reads, depending on whether the READ_COMMITTED_SNAPSHOT database option is enabled. Since wee enabled READ_COMMITTED_SNAPSHOT SQL Server will use versioning instead of locks.
ALTER DATABASE <database name>
SET READ_COMMITTED_SNAPSHOT ON
WITH ROLLBACK IMMEDIATE;