Natural/Composite key and IN (<-.) operator returning wrong results

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  [mkPersist sqlSettings, mkMigrate "migrateAll"]
  [persistLowerCase|
Person
    tid Text
    index Word
    age Int Maybe
    Primary tid index
    deriving Show
  |]

action :: ReaderT SqlBackend (NoLoggingT (ResourceT IO)) ()
action = do
  deleteWhere ([] :: [Filter Person])

  _ <- insert $ Person "tid1" 0 (Just 10)
  _ <- insert $ Person "tid1" 1 (Just 11)

  hmm <- selectList [PersonId <-. [PersonKey "tid1" 0, PersonKey "tid2" 1]] []

  liftIO $ print hmm

returns

[Entity {entityKey = PersonKey {personKeytid = "tid1", personKeyindex = 0}, entityVal = Person {personTid = "tid1", personIndex = 0, personAge = Just 10}},Entity {entityKey = PersonKey {personKeytid = "tid1", personKeyindex = 1}, entityVal = Person {personTid = "tid1", personIndex = 1, personAge = Just 11}}]

It should only return ("tid1", 0). Interestingly if I filter using

[PersonKey "tidlasdjflajsd1" 0, PersonKey "tid2" 1]

It returns []

It was deleting rows for mysterious reasons, and pretty broken, unless my intuition about (<-.) and filters is completely wrong. I thought it would translate to where (tid, index) IN (('tid1', 0), ('tid2', 1)). A workaround seems to be FilterOr a list of ==.?

I figured out how to get the SQL being used

SELECT "tid", "index", "age" FROM "person" WHERE ((("tid" IN ( ?, ?) ) and ("index" IN ( ?, ?) ))); [PersistText "tid1",PersistText "tid2",PersistInt64 0,PersistInt64 1]

so definitely not what I expected.

Start at the selectList entry point and the PersonId <-. filter handling, using the provided action and generated SQL to reproduce the composite-key query. Trace why the key components become independent IN clauses; done means the query returns only matching key pairs such as ("tid1", 0), without affecting unrelated rows.