But also no, RabbitMQ and Kafka and the like are clearly message buses and though they might also technically qualify as a DB it would be a poor descriptor.
Back when I worked in LA my CTO used to joke that most places use Microsoft Outlook as a database and Excel as BI tool.
[Source: I was friends with the guy who wrote it as well as other EToys employees. God that was a trainwreck.]
Would love to talk to anyone on the EToys team or anyone who has done something similar.
I'm @akamaozu on twitter.
I had to work on a tool that shows what's wrong with an assembly line: missing parts, delays, etc... So that management can take corrective action. Typical "BI" stuff but in a more industrial setting.
The company went all out on new technologies. Web front-end, responsive design, "big data", distributed computing, etc... My job was to use PySpark to extract indicators from a variety of data sources. Nothing complex, but the development environment was so terrible it turned the most simple task into a challenge.
One day, the project manager (sorry, "scrum master") came in, opened an excel sheet, imported the data sets, and in about 5 minutes, showed me what I had to do. It took me several days to implement...
So basically, my manager with Excel was hundreds of times more efficient than I was with all that shiny new technology.
That experience made me respect Excel and people who know how to use it a lot more, and modern stacks a lot less.
I am fully aware that Excel is not always the right tool for the job, and that modern stacks have a place. For example, Excel does not scale, but there are cases where you don't need scalability. An assembly line isn't going to start processing 100x more parts anytime soon, and one that does will be very different. There are physical limits.
Confluent, the company behind Kafka, are 100% serious about Kafka being a database. It is however a far better database than MongoDB.
Many of my employer's applications started out as a shared spreadsheet or Access database.
Our development team worked with the users and built a web application to solve the same problem.
This approach has a lot of advantages:
* The market exists and has an incumbent. There's a lower risk of a write-off.
* The users are open to process changes. You still have to migrate people off of the spreadsheet, though.
* It's easy to add value with reporting, error checking, concurrent access, and access control.
* You can import the existing data to make the transition easier. This will require a lot of data cleaning.
Edited to add the following text from another post.
You can cover most of the requirements with a set of fixed fields.
The last 10% to 20% of the use cases requires custom reports and custom fields.
Users should be able to define their own reports and run them without your involvement.
They should also be able to define custom field types with validation, data entry support, etc.
If your web application has these two features and other advantages then you should be able to replace Excel.
ksqldb is actually a database on top of this.
The thing is that they have an incrementally updated materialized view that is the table, while the event stream is similar to a WAL ("ahead of write logs?" in this case).
Because eventually you can't just go over your entire history for every query.
