BUG #3264: SPI: int64's sometimes returned by value sometimes by reference - Mailing list pgsql-bugs

The following bug has been logged online:

Bug reference:      3264
Logged by:          Adam Kunen
Email address:      adam.kunen@gmail.com
PostgreSQL version: 8.2.4
Operating system:   Ubuntu 7.04 - AMD64
Description:        SPI:  int64's sometimes returned by value sometimes by
reference
Details:

I have the ubuntu standard install of postgresql (including devel headers,
etc) for the 64-bit platform.

I have noticed some discrepencies with 64-bit values in tuples.
For a given row with multiple int8's I have noticed sometimes the value will
be passed by value and sometime by reference.

On my platform a int is 32-bit, long is 64-bit.

The DatumGetInt64 breaks for this because it seems to just be
dereferencing/casting a pointer, as defined as:

#define DatumGetInt64(X) (* ((int64 *) DatumGetPointer(X)))

So in my C trigger code I have been forced to make a wrapper around
SPI_getbinval to get my int64's that looks at the
TupleDesc->attrs[x]->attrbyval to determine which course of actions..
this is my wrapper:

int64 wrapper_get_int64(HeapTuple tup, TupleDesc desc, int colnum, bool
*isnull)
{
    // get the value or pointer
    Datum tmp = SPI_getbinval(tup, desc, colnum, isnull);

    // if its null, return 0
    if(*isnull)return 0;

    // if its pass by value, return the int64
    if(desc->attrs[colnum-1]->attbyval)return (int64)tmp;

    // if its pass by reference, deref and return
    else return DatumGetInt64(tmp);

}


This works great for me.

In all of the examples and contrib code i don't see anyone checking this,
all I see are examples like:

DatumGetInt64(SPI_getbinval(tup, desc, colnum, isnull));

So maybee this is not a bug... maybe a nice note about this in the docs
would be good.  But it seems to me that some of the contrib code could fail
on a 64-bit platform when 64-bits can be passed by value.

If i'm missing something here, let me know :)

thanks
-Adam Kunen