Re: PageGetMaxOffsetNumber

On Sun, 15 Dec 2002 23:49:57 -0300, Alvaro Herrera
<alvherre(at)dcc(dot)uchile(dot)cl> wrote:
>PageGetMaxOffsetNumber (the upper bound) returns a consistent value
>that's far too high (4294967291, 0xFFFFFFFB)

Alvaro, maybe this comment from bufpage.h can shed some light on it?

/*
* PageGetMaxOffsetNumber
* Returns the maximum offset number used by the given page.
* Since offset numbers are 1-based, this is also the number
* of items on the page.
*
* NOTE: to ensure sane behavior if the page is not initialized
* (pd_lower == 0), cast the unsigned values to int before dividing.
* That way we get -1 or so, not a huge positive number...
*/

#define PageGetMaxOffsetNumber(page) \
(((int) (((PageHeader) (page))->pd_lower - SizeOfPageHeaderData)) \
/ ((int) sizeof(ItemIdData)))

0xFFFFFFFB is -5.
With SizeOfPageHeaderData == 20 and sizeof(ItemIdData) == 4 you get
this result for pd_lower == 0.

Servus
Manfred