Postgres diskspace usage, indexing on TPH

[oskogstad]

[elsand]

Refinement:

See comment on #1497.

Actors do also carry alot of duplication, as the name of the actor is resolved immediately and stored in full. A better approach would be to have a internal "ActorName" table, which is referred to by id from each actor object within a dialog aggregate.

Name resolution should still happen immediately, but instead of storing to the actor-entity directly, a lookup for that identifier/name pair is performed, and if it matches, a reference to that actorname is stored. If no match is found (either the actor is previously unseen, or has changed name), a new entry is stored and referred to by the actor-object. This will effectively normalize the name property of the actor entity, while maintaining immutability with regards to name changing etc.

Edit: added a separate issue for this: #1669