> I remember going through this. Other backends will use pg_subtrans to
> know what transactions are in progress. They have to do the standard
> lookups to find the status of the parent transaction. The backend-local
> list of xids is needed so the commit can clean up those subtransaction
> xids so that later transactions don't have to use pg_subtrans.
Is there some solution whereby the common case (99.999% of transactions
won't be subtransactoins) is fast, and the uncommon case of being in a
subtransaction is slower?
Chris