Skip to main content

NoSQL Data Modelling

Recently in one of the project we planned to use some NoSQL  Document database. One of the reasons we though document database would be a great fit was that we could get started without setting up any DB schema and start shoving entities into the document database.
Nothing can be further from the truth. Data modeling is as essential and as fundamental an exercise for NoSQL stores as it is for RDBMS. It is just that the concepts are different as compared to RDBMS where normalization\de-normalization provide some guidance. In my pursuit to understand how to model data for a document database i came across some great reference material that i want to share here.

I believe this is enough content for one to have a decent understanding on the topic and get going with the real modeling.

Comments

bryan said…
I would clarify to this extent: DATA modeling is about the data. DATABASE modeling is about storing the data for accuracy, flexibility, velocity, reliability and all those other system attributes (the "-ities") that comes with implementation choices.

DATA modeling strives to make the data understandable. DATABASE modeling strives to make the data accessible. Two very different objectives, and two very different tasks.

I agree that any implementation of a database will require some degree of thought and design -- unless, of course, you don't care about those "-ities".

I once placed a wastebasket full of discarded printouts and scrap paper onto a table, pointed to it, and said "This is a database. Not a very good one, because finding the data in it is inefficient and unreliable and sometimes the data you find is wrong, or the data you're looking for is missing. But this wastebasket full of paper is a database. Our goal, as database modelers and designers is to improve on this."

So it is with every innovation that comes along. Does it improve on the last version of our wastebasket? And was that just by accident, or did you think about it first? Thinking about it is "modeling".

Popular posts from this blog

Caching Images downloaded from web on Windows Phone Isolated storage

I was helping on a Windows Phone application where the requirement was to cache the images the phone downloads on the isolated storage for offline viewing.
I wanted a solution which was simple and as transparent as possible. While researching I found  someone wrote a Silverlight converter for loading images from isolated storage. Taking that as a base I created a converted which can
Load image from web (http + https), and persist it to isolated storage.In case of network connectivity issues can load the same image from isolated storage. It does that by mapping the http url to a isolated storage location.In case the network is down and the image is neither there in cache, loads a default image, passed as parameter to converter.Here is the gist for the implementation.


To use the converter
Import the name space.Declare the converter as resource.Set the Image Source Property to use this converter like this 

IIS Url Rewrite and HTTP POST data

If you play around with IIS Url Rewriting rules and try to do redirects on an HTTP POST you loose your POST data.

To make sure you get the post data you have to set the `redirectType` to `Temporary` within your rules. So the action configuration looks like this

<action redirectType="Temporary" type="Redirect" url="http://{HTTP_HOST}{REQUEST_URI}"> </action>
You may think what scenario warrant a POST request redirect. We faced one such scenario while doing SSO with a federated Identity Provider (IP)  such as Google, Azure AD. In federated authentication scenario once the user is authenticated by the IP, it redirects back to your site with claim tokens in a POST request over secure channel (https). In our case we wanted to redirect to user back http after receiving the request. But any redirects were causing loss of token. By doing a 307 (Temporary) redirect we were able to preserve the post data.