Is tag historian module an absolute must have? If I want to simply store some data on an SQL database and display simple trends would I lose logging and display capability every two hours because the historian is not licensed?
No, but you will loose the ability to use certain components, such as the Easy Chart in Vision or the Power Chart in Perspective.
You absolutely can develop your own scripts that insert and query historical data to/from a database.
The Tag Historian module just makes it "easier". Or better said, more approachable for the "basic" Ignition user.
NOTE: That by "basic", I mean someone who is not well versed and/or has no desire to use the more advanced techniques that make Ignition such an extremely flexible product.
Thanks.
To kind of extend on what @lrose said, you can also use transaction groups as a way to do this if you have that module.
If you don't have either of those, please don't just throw system.db.runPrepQuery into tag change scripts. Typically, we have our global scripting project contain historization functions that can collect the tag path or whatever identifier you are using. Keeping your tag change scripts tidy will help you in the long run for maintainability and scalability imo.
Plus, reusability is something you want and if you have one function to change for all tag collection then that's more time you save.
You only lose the tag pens functionality of the EasyChart. The DB pens will work fine.
( I have clients who buy Ignition with a limited client count UI license and neither Historian nor SQL Bridge. All DB inserts/updates need to be scripted, and certain components or parts of components break, but it makes a really affordable base for HMIs. )