[emodendroket]

It's also an option when the properties of objects going in the table are going to be wildly different or are not known at write time.

[mason55]

This is a candidate for something like a schemaless datastore or a PostgreSQL JSONB column. Depending on your choice of datastore you can still at least get some indexing and schema help if you choose. With EAV you generally throw all of that out.

[emodendroket]

A whole separate datastore sounds like overkill in a lot of cases.