Gregory Stark wrote:
> "Bruce Momjian" <[EMAIL PROTECTED]> writes:
> > I have added another idea for index-only scans to the TODO list:
> >> A third idea would be for a heap scan to check if all rows are visible
> >> and if so set a per-table flag which can be checked by index scans.
> >> Any change to the table would have to clear the flag. To detect
> >> changes during the heap scan a counter could be set at the start and
> >> checked at the end --- if it is the same, the table has not been
> >> modified --- any table change would increment the counter.
> I think I would prefer to address this in the same infrastructure as the
> dead-space-map. That way you're not dependent on having no updates happening
> on the table at all. Any tuples on pages which contain no in-doubt tuples
> could have their visibility check skipped but when you come across a tuple on
> a page which has been modified since the last vacuum then you have to check
> the visibility.
Yea, the bitmap/page idea is already on the TODO list. This was just a
less granular idea.
Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us
+ If your life is a hard drive, Christ can be your backup. +
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