Unlogged tables seems to me to follow a similar goal. Obviously GiST indexes are not supported there. Do you know the technical reason?
GiST using serial numbers of operations for concurrency. In current implementation xlog record ids are used in capacity of that numbers. In unlogged table no xlog records are produced. So, we haven't serial numbers of operations. AFAIK, it's enough to provide some other source of serial number in order to make GiST work with unlogged tables.
Do you see some synergy in your work on fast GiST index building and unlogged tables?
With tecnhique discussing in this thread GiST build can win form unlogged as much as with regular build.
