[doctrine] Normalize discriminator column / discriminator map as database table

Normally when we 're talking about single table inheritance in doctrine orm, we use a discriminator column with a discrimonator map, that maps every possible entity to a database table. That 's fine and works as designed and from my point of view that 's it. No need to change that.

One of my customers wants me to normalize the discriminator column. Since the values in the discriminator column are repeated, it is intended that these values are stored in a table to be joined and are thus unique. Accordingly, the discriminator column should only have a foreign key to this table, which roughly maps the discriminator map.

Is that possible? Has anyone tried this before? Any hints?