Обсуждение: number of attributes in page files?

Is it possible to get rid of the "t_natts" fields in the tuple header? Is this field only for "alter table add/drop"
support?Then it might 
possible to get rid of it and put the "t_natts" field in the page header, not the tuple header, if it can be assured
thatwhen updating/inserting 
records only a compatible (a page file with the same number of attributes) page file is used. Especially master-detail
tableswould  
profit from this, reducing the tuple overhead by another 9%.

Might this be possible?

Regards,
    Mario Weilguni

Mario Weilguni <mweilguni@sime.com> writes:
> Is it possible to get rid of the "t_natts" fields in the tuple header?
> Is this field only for "alter table add/drop" support?

"Only"?  A lot of people consider that pretty important ...

But removing 2 bytes isn't going to save anything, on most machines,
because of alignment considerations.

            regards, tom lane

Am Freitag, 11. Oktober 2002 14:12 schrieb Tom Lane:
> Mario Weilguni <mweilguni@sime.com> writes:
> > Is it possible to get rid of the "t_natts" fields in the tuple header?
> > Is this field only for "alter table add/drop" support?
>
> "Only"?  A lot of people consider that pretty important ...

With "only" I mean it's an administrative task which requires operator intervenation anyways, and it's a seldom needed
operationwhich may take longer, when 
queries become faster.

>
> But removing 2 bytes isn't going to save anything, on most machines,
> because of alignment considerations.

ok, I did not consider alignment, but the question remains, is this easily doable? Especially because only one another
bytehas to be saved for 
real saving on many architectures, which is t_hoff. IMO t_hoff is not useful because it can be computed easily. This
wouldgive 20 byte headers instead of 23 (24) bytes as it's now.  
This is 17% saved, and if it's not too complicated it might be worth to consider.

Best regards,
    Mario Weilguni