> To support this sanely though wouldn't you need to know which language rule a
> tsvector was generated with? Like, have a byte in the tsvector tagging it with
> the language rule forever more?
No. As corner case, dictionary might return just a number or a hash value.
>
> What I'm wondering about is if you use a different rule than what was used
> when an index entry was inserted will you get different results using the
> index than you would doing a sequential scan and reapplying the operator to
> every datum?
Rules are apllyed during creattion of tsvector, not during indexing of
tsvectors. So, sequential and index scan will return identical results.