On Thursday, June 07, 2012 04:27:32 PM Robert Haas wrote:
> On Thu, Jun 7, 2012 at 9:41 AM, Andres Freund <and...@2ndquadrant.com>
wrote:
> >> Proposed patch attached. This adds some more comments in various
> >> places, and implements your suggestion of retesting the visibility-map
> >> bit when we detect a possible mismatch with the page-level bit.
> >
> > Thanks, will look at it in a bit.
I wonder if
/* mark page all-visible, if appropriate */
if (all_visible && !PageIsAllVisible(page))
{
PageSetAllVisible(page);
MarkBufferDirty(buf);
visibilitymap_set(onerel, blkno, InvalidXLogRecPtr,
vmbuffer,
visibility_cutoff_xid);
}
shouldn't test
if (all_visible &&
(!PageIsAllVisible(page) || !all_visible_according_to_vm)
instead.
Commentwise I am not totally content with the emphasis on memory ordering
because some of the stuff is more locking than memory ordering. Except that I
think its a pretty clear improvement. I can reformulate the places where I
find that relevant but I have the feeling that wouldn't help the legibility.
Its the big comment in vacuumlazy.c, the comment in nodeIndexonly.c and the
one in the header of visibilitymap_test. Should be s/memory-
ordering/concurrency/ except in nodeIndexonlyscan.c
The visibilitymap_clear/PageClearAllVisible in heap_multi_insert should be
moved into the critical section, shouldn't it?
Regards,
Andres
--
Andres Freund http://www.2ndQuadrant.com/
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