I'm surprised I haven't seen more discussion of how tags are an entry point into plain-old data architecture. It should be obvious that by the time you're using tags for queries like "start-date: BEFORE 2022-03-01", you've created an inner-platform where you're building a plain-old relational database on top of your tags. Stop what you're doing and elevate "start date" out of tag-land and into a more structured representation with more application support.
Many enterprise databases add a memo field called "Comments" to almost every table. Clients very often end up coming up with their own guidelines about how to embed various information in the comments fields that the primary structure is missing. Looking over how clients are using the "comments" fields is a great way to discover new things that should be formally incorporated into the structure of your data architecture. Similarly with tags.
Look at tags as a starting point for adding a bit of loose structure to the frontiers of your data architecture. Mix them in with more structured data architecture. Be ready to "graduate" tags up to the next level of structure when it becomes appropriate. Stop worrying about how to make tagging perfect and embrace it for what it is: an easy way to get started on modeling the parts of the domain that you haven't spent a long time thinking about yet. A good way to understand how users want to use your system. Something you're always revisiting, cleaning up, and using as a source of inspiration. If you see some tags getting out of hand, don't try to improve your tagging system; instead take what those tags are trying to represent and add more structured fields and queries for them. This pipeline of less to more structure should be constantly playing out in a healthy, evolving system.
Relatedly, comments fields are the bane of data compliance exercises. You think you’ve caught everywhere a customer’s information might be stored, and then at the last minute you find out support have been putting phone numbers in the comments field because they had nowhere else to put it.
What a weird decision to store dates in tags, it looks like bad design. Fully agree with the primer to data architecture, I've seen people almost getting to the point of writing DSL over tags. Madness!
As someone who dabbled in adding basic tagging to a database recently, this take feels absolutely spot-on. I’ll draw on it when evolving our system forward.
Many enterprise databases add a memo field called "Comments" to almost every table. Clients very often end up coming up with their own guidelines about how to embed various information in the comments fields that the primary structure is missing. Looking over how clients are using the "comments" fields is a great way to discover new things that should be formally incorporated into the structure of your data architecture. Similarly with tags.
Look at tags as a starting point for adding a bit of loose structure to the frontiers of your data architecture. Mix them in with more structured data architecture. Be ready to "graduate" tags up to the next level of structure when it becomes appropriate. Stop worrying about how to make tagging perfect and embrace it for what it is: an easy way to get started on modeling the parts of the domain that you haven't spent a long time thinking about yet. A good way to understand how users want to use your system. Something you're always revisiting, cleaning up, and using as a source of inspiration. If you see some tags getting out of hand, don't try to improve your tagging system; instead take what those tags are trying to represent and add more structured fields and queries for them. This pipeline of less to more structure should be constantly playing out in a healthy, evolving system.