From: Alex B. <boi...@in...> - 2006-02-17 21:45:03
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Thompson, Bryan B. wrote: >If a reader needs to leave a timestamp mark every time it reads a >record, then that is not going to be very efficient since it turns >reads into read + write operations. Some kinds of MVCC require >read timestamps, but I think that we need to find a variation which >does not. > > I'm most definitely not in favor of any MVCC approach that requires readers to place timestamps on record. >I personally like the idea of a log structured store very much and >I am also thinking in terms of how to combine MVCC with that approach. >It seems a natural fit. Log structured stores can help to get rid of >some hotspots in allocation of records. > > Agreed. >However, if by "log structured" store you mean an append only store >(which is how I interpret it) then I think that we also need to provide >for people who want a store with destructive overwrites. I.e., where >the space from "old" versions eventually gets reused rather than >providing an immortal history of the consistent states of the database. > >I personally think that we can do both. The binary formats will differ, >but the main difference is in the persistent record allocation logic if >the store is already using MVCC. > > I also think we can do both. (I didn't mean to imply append-only store) alex |