> If PostgreSQL wants to stay MVCC, then we should imho forget > "overwriting smgr" very fast. > > Let me try to list the pros and cons that I can think of: > Pro: > no index modification if key stays same > no search for free space for update (if tuple still > fits into page) > no pg_log > Con: > additional IO to write "before image" to rollback segment > (every before image, not only first after checkpoint) > (also before image of every index page that is updated !) I don't think that Oracle writes entire page as before image - just tuple data and some control info. As for additional IO - we'll do it anyway to remove "before image" (deleted tuple data) from data files. Vadim ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://www.postgresql.org/search.mpl
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Philip Warner
- Re: [HACKERS] Plans for solving the VACUUM problem Tom Lane
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- Re: [HACKERS] Plans for solving the VACUUM problem Philip Warner
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim
- RE: [HACKERS] Plans for solving the VACUUM problem Mikheev, Vadim