Another Relational vs. NoSQL Kinda Day

I came across this article on schema/data modelling in Cassandra vs. a traditional SQL counterpart. In my current job, we have an input stream that comprises of several files through the day that each contain the same structured data. Currently we have an ETL tool that ingests these files and spits them out into different SQL Server tables. There are some ETL jobs that then take this data and further denormalize it. We have two issues at a database level. Firstly, some performance issues, but I am not convinced they are due to this being a relational database. I think in most cases we could use SQL features and techniques like indexing, denormalization, etc. to alleviate most of these performance issues. The second concern is size. Due to the size of the tables, the indexes become huge over time. If your query is not optimized, one bad read on this table can kill you. If you need to perform a time consuming job, it is going to lock up the table and the ingestion essentially has to be stopped. I have been thinking about whether a NoSQL option like Cassandra would help in this case. Cassandra gives you horizontal scaling and faster reads. Cassandra also encourages (careful) data duplication and denormalization. The whole one table per query type thinking may help.

That’s all. No solutions for today. Just thoughts and questions.

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Another Relational vs. NoSQL Kinda Day

Conversational Commerce using Microsoft Bot Framework

I just posted a conversational commerce bot I built for prototype using Microsoft Bot Framework over at my Github. It uses LUIS for natural language processing and makes use of Bot State Service. Detailed tutorial coming soon. But if you can’t wait, head on over to my github page, download the source code and start playing with it.

sampleemulatorchat1

Conversational Commerce using Microsoft Bot Framework

First GitHub Project – MVC Web API using Google OAuth

I finally ended up activating my GitHub account that I signed up for years ago, and publish my first GitHub project. It is a MVC Web API project that uses Google OAuth for authentication. You can see it here.

Even though a lot of the MVC project templates supposedly come with external authentication fully configured, in practice I found that to be quite untrue (other than the single page app template). I could only get this to work after pulling information from several different blogs. I started off with an empty Web API project and only build pieces I needed as I went.

The other thing I was trying to do was send POST messages using Postman to google for authentication, and that did not work at all for me. I did get an authentication token back from Google, but I kept getting 401 when trying to make a POST call to the authorized function. Possible reasons could be, misconfiguration of Postman (even though I did verify everywhere else, and unauthorized GET was working fine), Google blocking it because it wants a consensual mouse click authorizing app access, or something else. I gave up on Postman and made AJAX calls on a simple HTML page.

mvc-web-api-google-oauth

So, if you are looking to add external authentication into your .NET MVC Web API, maybe this project on GitHub would be of some use to you!

First GitHub Project – MVC Web API using Google OAuth

Show Current Git Branch in PowerShell

If you happen to switch between branches a lot, or find yourself doing git branch to see what branch you are currently on, you can easily modify your PowerShell profile to show your current active branch right in the prompt. Here is how.

Step 1

Open powershell profile for edit by entering “notepad $profile” in powershell. This will open your PowerShell profile located here: C:\Users\yourname\Documents\WindowsPowerShell

Step 2

Add the following function in the profile definition.

function prompt {
$host.ui.rawui.WindowTitle = $(get-location)

$prompt_string = “PS ” + $(get-location) + ” [”

if(Test-Path .git) {
git branch | foreach {
if ($_ -match “^\*(.*)”){
$prompt_string += $matches[1] + ” ]> ”
}
}
}
else{
$prompt_string = “PS> ”
}

Write-Host ($prompt_string) -nonewline -foregroundcolor yellow
return ” ”
}

Step 3

Save and re-open the powershell. Your prompt should now show as following in yellow with branch name showing in the square brackets:

PS C:\Projects\foo [ x.x.currentBranch ]>

Show Current Git Branch in PowerShell

ACID vs. BASE

Good article on ACID vs. BASE attributes of a database you can read here. To recap ACID means 

Atomic: Everything in a transaction succeeds or the entire transaction is rolled back.

Consistent: A transaction cannot leave the database in an inconsistent state.

Isolated: Transactions cannot interfere with each other.

Durable: Completed transactions persist, even when servers restart etc.

And BASE refers to: 

Basic Availability

Soft-state

Eventual consistency

ACID vs. BASE

When and when not to use NoSQL

I came across this great article on Microsoft Azure Docs on NoSQL vs. SQL. In the development world, there are new technologies coming down like rain every day. It is easy to get caught up in the latest and biggest trend and have a tendency to replace your current favorite technology (a hammer) for any problem (a nail) with a different technology (a different hammer). It is important to not lose focus of what are the true applications of any new technology, and when to use it or not use it.

The Microsoft article example gives a great example on a social site where you may have a user making a post with different media that get comments and likes by other users. To think of it in a purely relational database sense, you may end up creating different tables to host users, posts, media types, comments, etc. with one-to-many or many-to-many relationships going every which way. And to do something simple like showing a post from a user may require you to run joins on several of these tables. Definitely not great for performance.

nosql-vs-sql-social

In comparison, in a document based NoSQL database, you could have entire documents saved with all the relevant information for a particular post, assigned to a user. It would be very performant unlike the multi-table, multi-relationship joins all over solution an RDBMS would offer.

nosql

There are things that relational databases are good at, for instance

  • Relational Queries
  • Defined and uniform table structure (all entries have same fields)
  • Well Defined Schema (though adding properties requires more work)
  • Structured Data
  • Vertical Scaling (More RAM, More Processing Power)

and there are things NoSQL storage is good at, for instance

  • Non-relational data (JSON, key-value pairs, etc.)
  • Ease of adding new properties
  • Unstructured data
  • Availability of Consistency (CAP Theorem)
  • Horizontal Scaling (Add Servers)
When and when not to use NoSQL

Clean Architecture of Microservices

I came across this article from Robert C. Martin (Uncle Bob) about Microservices architecture. In it he argues that any architecture whether microservices or traditional 3-tier or anything in between, needs to be designed to be decoupled from deployment strategy. He argues that the code should be unaware of whether it will eventually be deployed as microservices or DLLs or anything else. And that you shouldn’t bake deployment strategy into your code. Interesting article for sure. You can read the complete article on his site here

Clean Architecture of Microservices