Re: More heap tuple header fixes

Your patch has been added to the PostgreSQL unapplied patches list at:

    http://candle.pha.pa.us/cgi-bin/pgpatches

I will try to apply it within the next 48 hours.

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Manfred Koizar wrote:
> On Sat, 20 Jul 2002 16:27:14 -0400, Tom Lane <tgl@sss.pgh.pa.us>
> wrote:
> >I'd recommend redesigning the HeapTupleHeaderSet macros so that they
> >do not do any setting of t_infomask bits, or even take any conditional
> >action based on them,
>
> The HEAP_XMIN_IS_XMAX bit is exclusively managed by these macros.
> Pulling the handling of this bit out of the macros and spreading it to
> the places, where the macros are used, cannot make the whole thing
> more robust.  This would mean, the caller had to decide whether to
> store Cmax into t_cid or t_xmax...
>
> > but solely Assert() that the bits are already
> >in the appropriate state to allow storing of the value to be stored.
> >Then, all uses have to be checked to ensure that t_infomask is coerced
> >into the right state *before* doing HeapTupleHeaderSetFoo.
>
> Apart from HEAP_XMIN_IS_XMAX this was my intention;  we already do
> this with HEAP_MOVED.  I could add an assertion to SetCmax:
>     Assert(!((tup)->t_infomask & HEAP_XMAX_INVALID));
>
> OTOH I thought about putting *more* logic into the macros to make
> their use less fragile.  For example SetXmaxInvalid could set the
> HEAP_XMAX_INVALID bit, likewise SetCminInvalid with XMIN_INVALID.
>
> Anyway, with this patch applied the heap tuple header changes should
> be able to survive the next two weeks.  I don't want to hack together
> a quick change now, before I go on vacation.  Let's find the perfect
> solution, when I'm back ...
>
> Servus
>  Manfred
>
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