Greetings,

I have seen this topic come a few times in the past but noone really gave a good reason to do this. I hope the reasons here changes developers minds to write an extension.

In our system we have over 800 tags and will grow incredibly big once we start face recognition as well.

As we have half a terrabyte of photos and videos and growing fast, we have organised them into general albums, but find detailed tagging and advance searching as the best way to find what you are looking for fast.

Shotwell also went through the same process a few years ago and have created an industry compliant hierarchical tagging setup. http://yorba.org/shotwell/help/tag.html. This would be perfect for piwigo (and for the write_metadata extension). As they have done all the hard work of discussing and picking a proper compliant standard, then it is just a matter of implementing it in Piwigo.

By grouping, it will be easier for users to find and select fast the relevant tags when doing an advance search.

Thanks for considering Piwigo team !