On Thu, 23 Jun 2005, Tom Lane wrote:

> Pavel Stehule <[EMAIL PROTECTED]> writes:
> +                     /* If any argument is null, then result is null (for 
> Are you sure about that?  The only reference I could find says that
> these functions are not strict in Oracle:
> http://download-east.oracle.com/otn_hosted_doc/rdb/pdf/sql_ref_v71_vol1.pdf
> on page 2-185:
>  The NULL keyword can appear in the list but is ignored. However, not all 
>  value expressions can be specified as NULL. That is, a non-NULL value 
>  expression must be in the list so that the data type for the expression
>  can be determined. 
>  The GREATEST and LEAST functions can result in NULL only if at run time 
>  all value expressions result in NULL. 
> The strict interpretation is mathematically cleaner, no doubt, but
> offhand it seems less useful.

I know it, But when moustly PostgreSQL function is strict I desided so 
greatest and least will be strict. There is two analogy:

one, normal comparing which implicate strinct
aggregate function which ignore NULL.

what I have to chose? For compatibility there isn't biggeer changes. Only 

//if (*isNull)
//  return value;
if (result && *isNull == false)
   locfcinfo.arg[0] = result;

foreach(arg, ..)
        if (IsA(e, Const))
                if (!((Const *) e)->constisnull)
                        newargs = lappend(newargs, e);
if (newargs == NULL)
        return (Node *) makeNullConst(varargexpr->..);

Tom I don't know, what is better. Maybe Oracle,


least(nullif(col2, +max), nullif(col2, +max)) isn't really readable, but 
it's "precedens" for PostgreSQL. I selected more conservative solution, 
but my patches are only start points for discussion (really) :).

Please, if You think, so Oracle way is good, correct it.

Best regards

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