Zeugswetter Andreas DCP SD wrote: > > > > But you could do the indexes first and remember how far you > > can vacuum > > > the heap later. > > > > But the indexes _can't_ be done first; you _first_ need to > > know which tuples are dead, which requires looking at the > > table itself. > > If we already had the "all tuples visible" bitmap I think we could > first scan the bitmap and decide whether we can afford to look > at the visibility info for each entry in the index. > > We only collect the ctids before so we don't have the inefficient > lookups, > but if we can avoid the lookup in most cases it would again be > attractive.
The problem is that index to heap lookups are very slow. -- Bruce Momjian http://candle.pha.pa.us SRA OSS, Inc. http://www.sraoss.com + If your life is a hard drive, Christ can be your backup. + ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
