Bruce Momjian <[EMAIL PROTECTED]> writes: > Tom Lane wrote: >> ... but we won't come out ahead unless advancing xmin >> intra-transaction really helps, and I'm not sure I believe that (except >> in the special case of VACUUM, and we already have a solution for that, >> which would be independent of this).
> The improvement is going to be a win for multi-statement transactions > --- the only question is how often are they long-running. Uh, no, that's not very clear. A long-running transaction will be a VACUUM bottleneck because of its own XID, never mind its xmin. To make this helpful, you have to posit a lot of overlapping long-running transactions (such that the distance back to GlobalXmin might average about twice the distance back to the oldest live XID). That's not impossible but I wonder whether it's not mostly a token of bad application design. > It does seem best to put this on the TODO for 8.4, and I will do that > now. Agreed. Quite aside from the time needed for a reasonable implementation, we'd really need to do more performance-testing than we have time for now. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org