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
We plan to tag also contacts and products using the same tag relation,
but different invoice_tag, contact_tag, and product_tag relations for
each one. However, the logic is the same for all three, hence it makes
more sense to put it into a PL/pgSQL with dynamic SQL. Moreover, the
SQL for tagging in add_invoice and edit_invoice where almost exactly
the same, the only difference was deleting the existing tags when
editing.
I do not execute the tag_relation function in its test suite because
by itself it does nothing without supporting invoice_tag, contact_tag,
or any such relation, so it is being tested in the suite for
tag_invoice.
jordi fita mas