Re: access method: are disk pages mandatory?

Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> On 23/06/10 18:17, Leonardo F wrote:
>> I'm not getting it: am I supposed to use the "disk page format" when
>> writing an index access method, or it's just a "good practice" because
>> it makes the handling easier? Given the docs it looks "recommended",
>> but the comment on the code sounds more "mandatory".

> It's recommened because it makes life easier. Even if you don't use the 
> normal page format, I think you need to have the LSN at the beginning of 
> the page. The rest is up to you.

The bufpage.h comment is ancient and might not be 100% gospel anymore.
However, I believe the buffer manager does assume that any page in
shared buffers has a standard page header including LSN.  It definitely
assumes there's an LSN, and I think we have validity checks on the other
page header fields somewhere inside ReadBuffer.  You don't however need
to use the item-and-item-pointer-array structure if it's not useful to
you.
        regards, tom lane