On Apr 18, 2014, at 1:51 PM, Atri Sharma <atri.j...@gmail.com> wrote:
> Counting clock sweeps is an intersting idea. I think one concern was > tracking hot buffers in cases where there is no memory pressure, and > hence the clock sweep isn't running --- I am not sure how this would > help in that case. > Yes, we obviously want a virtual clock. Focusing on the use of gettimeofday seems silly to me: it was something quick for the prototype. The problem with the clocksweeps is they don’t actually track the progression of “time” within the PostgreSQL system. What’s wrong with using a transaction number or some similar sequence? It would accurately track “age” in the sense we care about: how long ago in “units of real work being done by the DB” something was added. —Jason
