On Wed, Sep 07, 2005 at 01:20:27PM -0400, Tom Lane wrote: > Anyway the fundamental insight has been completely lost here. The > original point was that cmin and cmax are only interesting within the > originating transaction, and not to anyone else, and thus perhaps don't > need to be kept in permanent storage; while xmin/xmax are different > animals because they *are* of interest to other transactions.
I'm curious to know how can you store the cmin/cmax pair completely out of the tuple. It's easy to see how to store a single identifier in each tuple that would be an index to a structure in local memory. However, to eliminate both you'd have to keep a list of all tuples you have created or obsoleted, with the cmin and cmax of each. This seems like an awful amount of memory. -- Alvaro Herrera -- Valdivia, Chile Architect, www.EnterpriseDB.com "I can't go to a restaurant and order food because I keep looking at the fonts on the menu. Five minutes later I realize that it's also talking about food" (Donald Knuth) ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq