In nbtree.c there's a path that calls btvacuumscan to gather statistics if
there aren't already statistics. I'm not exactly clear how this code path is
reached but that's not my question. There's a comment that "there's no need to
go through all the vacuum-cycle-ID pushups" in this case because no deletions
are being performed. 

I don't see how the lack of deletions is relevant to needing vacuum-cycle-ID.
AFAICT there's still a risk that someone will come along and do a page split
underneath this scan and if the page is to the left of the scan it will be

        IndexVacuumInfo *info = (IndexVacuumInfo *) PG_GETARG_POINTER(0);
        IndexBulkDeleteResult *stats = (IndexBulkDeleteResult *) 

         * If btbulkdelete was called, we need not do anything, just return
         * the stats from the latest btbulkdelete call.  If it wasn't called,
         * we must still do a pass over the index, to recycle any 
         * pages and to obtain index statistics.
         * Since we aren't going to actually delete any leaf items, there's no
         * need to go through all the vacuum-cycle-ID pushups.
        if (stats == NULL)
                stats = (IndexBulkDeleteResult *) 
                btvacuumscan(info, stats, NULL, NULL, 0);


---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster

Reply via email to