Question about FUNCDETAIL_MULTIPLE
I was wondering what the philosophy is behind letting an "ambiguous"
function be created in the first place. Is this for backwards
compatibility or perhaps for historical reasons? Could someone clarify
this please?
Consider the following example:
(
FYI:
parse_func.c->ParseFuncOrColumn->164
parse_func.c->ParseFuncOrColumn->810
parse_func.c->ParseFuncOrColumn->836
namespace.c->FuncnameGetCandidates->607
namespace.c->FuncnameGetCandidates->826
parse_func.c->ParseFuncOrColumn->224
)
-----------------------------------------------------------------------------
create or replace function foo1(int,int default 1,int default 2) returns
int as
$$
select $1+$2+$3
$$
language sql;
create or replace function foo1(int,int default 1) returns int as
$$
select $1+$2
$$
language sql;
select * from foo1(10,10)
ERROR: function foo1(integer, integer) is not unique
LINE 15: select * from foo1(10,10)
^
HINT: Could not choose a best candidate function. You might need to add
explicit type casts.
-----------------------------------------------------------------------------
--
Regards,
Gevik
2009/6/4 Gevik Babakhani <pgdev@xs4all.nl>:
I was wondering what the philosophy is behind letting an "ambiguous"
function be created in the first place. Is this for backwards compatibility
or perhaps for historical reasons? Could someone clarify this please?
This is +/- for historical reasons. We used original algorithm for
ambiguous function identification.
regards
Pavel Stehule
Show quoted text
Consider the following example:
(
FYI:
parse_func.c->ParseFuncOrColumn->164
parse_func.c->ParseFuncOrColumn->810
parse_func.c->ParseFuncOrColumn->836
namespace.c->FuncnameGetCandidates->607
namespace.c->FuncnameGetCandidates->826
parse_func.c->ParseFuncOrColumn->224
)-----------------------------------------------------------------------------
create or replace function foo1(int,int default 1,int default 2) returns int
as
$$
select $1+$2+$3
$$
language sql;create or replace function foo1(int,int default 1) returns int as
$$
select $1+$2
$$
language sql;select * from foo1(10,10)
ERROR: function foo1(integer, integer) is not unique
LINE 15: select * from foo1(10,10)
^
HINT: Could not choose a best candidate function. You might need to add
explicit type casts.
-------------------------------------------------------------------------------
Regards,
Gevik--
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Gevik Babakhani <pgdev@xs4all.nl> writes:
I was wondering what the philosophy is behind letting an "ambiguous"
function be created in the first place. Is this for backwards
compatibility or perhaps for historical reasons?
Neither; it's a feature, and one we quite like. For example, would you
really prefer that the six different versions of abs() had to have
different names?
regression=# \df abs
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+------+------------------+---------------------+--------
pg_catalog | abs | bigint | bigint | normal
pg_catalog | abs | double precision | double precision | normal
pg_catalog | abs | integer | integer | normal
pg_catalog | abs | numeric | numeric | normal
pg_catalog | abs | real | real | normal
pg_catalog | abs | smallint | smallint | normal
(6 rows)
Even if you were willing to do that, what about the forty-seven
distinct versions of "+"? Overloaded operators are not fundamentally
different from overloaded functions.
regards, tom lane
Tom Lane wrote:
Gevik Babakhani <pgdev@xs4all.nl> writes:
I was wondering what the philosophy is behind letting an "ambiguous"
function be created in the first place. Is this for backwards
compatibility or perhaps for historical reasons?Neither; it's a feature, and one we quite like. For example, would you
really prefer that the six different versions of abs() had to have
different names?regression=# \df abs
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+------+------------------+---------------------+--------
pg_catalog | abs | bigint | bigint | normal
pg_catalog | abs | double precision | double precision | normal
pg_catalog | abs | integer | integer | normal
pg_catalog | abs | numeric | numeric | normal
pg_catalog | abs | real | real | normal
pg_catalog | abs | smallint | smallint | normal
(6 rows)Even if you were willing to do that, what about the forty-seven
distinct versions of "+"? Overloaded operators are not fundamentally
different from overloaded functions.regards, tom lane
I understand the value of this future. This basically means that one has
to keep the function naming and argument types as simple as logically
possible in order to avoid situations like I described in my previous
example.
(Sorry for bothering you with questions likes this. I am trying to
understand PG)
--
Regards,
Gevik