On Thu, 2006-12-28 at 15:14 +0900, ITAGAKI Takahiro wrote: > Even if it is off, DSM are always recorded and updated.
The purpose of the patch, as I understand it, is performance. Can I ask what the performance overhead of this is for standard OLTP workloads? Do you have some performance numbers for VACUUM with/without this patch? Presumably it does speed things up considerably, but question is, how much? Is there a point where you VACUUM more than x% of a table that it is actually better to just VACUUM the whole thing, because of readahead? Is there a size of table for which keeps dsm information is not worthwhile? i.e. small tables -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
