Re: [PATCH] binary heap implementation

On 2012-11-20 14:03:12 -0500, Robert Haas wrote:
> On Thu, Nov 15, 2012 at 8:56 PM, Abhijit Menon-Sen <ams(at)2ndquadrant(dot)com> wrote:
> > [ new patch ]
>
> I went over this again today with a view to getting it committed, but
> discovered some compiler warnings that look like this:
>
> warning: cast to pointer from integer of different size
>
> The problem seems to be that the binary heap implementation wants the
> key and value to be a void *, but the way it's being used in
> nodeMergeAppend.c the value is actually an int. I don't think we want
> to commit a binary heap implementation which has an impedance mismatch
> of this type with its only client. The obvious solution seems to be
> to make the key and value each a Datum, and then clients can use
> WhateverGetDatum and DatumGetWhatever to pass whatever built-in data
> type they happen to have. I'm trying that approach now and will post
> an updated patch based on that approach if it seems to work OK and
> nobody suggests something better between now and then.

Sounds like a good plan, one other alternative would have been declaring
the parameters a size_t (and thus explicitly always big enough to store
a pointer, but also valid to store inline data) instead of using a
void*. But given there is DatumGetPointer/PointerGetDatum et al, using
the postgres-y datatype seems fine to me.

In the LCR case those really are pointers, so preserving that case is
important to me ;), but your proposal does that, so ...

Andres