On Wed, Apr 3, 2019 at 5:34 PM Kyotaro HORIGUCHI <horiguchi.kyot...@lab.ntt.co.jp> wrote: > I may be missing something, but it seems possible that > _mdfd_getseg calls it with segno > opensegs. > > | for (nextsegno = reln->md_num_open_segs[forknum];
Here nextsegno starts out equal to opensegs. > | nextsegno <= targetseg; nextsegno++) Here we add one to nextsegno... > | ... > | v = _mdfd_openseg(reln, forknum, nextsegno, flags); ... after adding one to opensegs. So they're always equal. This fits a general programming pattern when appending to an array, the next element's index is the same as the number of elements. But I claim the coding is weird, because _mdfd_openseg's *looks* like it can handle opening segments in any order, except that the author accidentally wrote "<=" instead of ">=". In fact it can't open them in any order, because we don't support "holes" in the array. So I think it should really be "==", and it should be an assertion, not a condition. -- Thomas Munro https://enterprisedb.com
