Re: equal() perf tweak

Is there a TODO here?

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Neil Conway wrote:
> Tom Lane <tgl@sss.pgh.pa.us> writes:
> > This does suggest that it might be worth making the struct layout be
> >
> >     int NodeTag;
> >     int length;
> >     foo *head;
> >     foo *tail;
> >
> > since this would avoid some padding overhead on a machine where pointers
> > are 8 bytes and need 8-byte alignment.  It probably doesn't help given
> > the current implementation of palloc, but why throw away padding
> > space?
>
> Interesting. I've heard in some shops it is standard policy to order
> the fields in all structs by their descending sizes (making allowances
> for platform-specific variations), so as to reduce padding. Do you
> think it would be worthwhile to systematically make this kind of
> reorganization throughout the backend?
>
> (Of course, we'd need to be weary of code that depends on order of the
> fields in structs, naturally -- such as the "NodeTag must be the first
> field" rule.)
>
> -Neil
>
>
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