It all started when i wanted to try to filter invoices by multiple tags
using an “AND”, instead of “OR” as it was doing until now. But
something felt off and seemed to me that i was doing thing much more
complex than needed, all to be able to list the tags as a suggestion
in the input field—which i am not doing yet.
I found this article series[0] exploring different approaches for
tagging, which includes the one i was using, and comparing their
performance. I have not actually tested it, but it seems that i have
chosen the worst option, in both query time and storage.
I attempted to try using an array attribute to each table, which is more
or less the same they did in the articles but without using a separate
relation for tags, and i found out that all the queries were way easier
to write, and needed two joins less, so it was a no-brainer.
[0]: http://www.databasesoup.com/2015/01/tag-all-things.html
It seems that we do not agree en whether the IRPF tax should be
something of the product or the contact, so we decided to make the
product have multiple taxes, just in case, and if only one is needed,
then users can just select one; no need to limit to one.