Thread: AW: functions returning records
> For the result from foo() you must somewhere define attributes (names). > Where? In CREATE FUNCTION statement? Possible must be: > > select name1, name2 from foo() where name1 > 10; Yes, optimal would imho also be if the foo() somehow had access to the where restriction, so it could only produce output, that the higher level is interested in, very cool. This would be extremely useful for me. Very hard to implement, or even find an appropriate interface for though. Andreas
> >> For the result from foo() you must somewhere define attributes >> (names). >> Where? In CREATE FUNCTION statement? Possible must be: >> >> select name1, name2 from foo() where name1 > 10; > > Yes, optimal would imho also be if the foo() somehow had access to the > where restriction, so it could only produce output, that the > higher level is interested in, very cool. This would be extremely > useful for me. Very hard to implement, or even find an appropriate > interface for though. You could easily implement it *in* the function foo IMHO. Since the function does some black magic to create the result set to begin with, you can change it to use parameters: select name1, name2 from foo(10, NULL, NULL) where name1 > 10;
On Wed, Jun 27, 2001 at 10:56:43AM +0200, Reinoud van Leeuwen wrote:
> >
> >> For the result from foo() you must somewhere define attributes
> >> (names).
> >> Where? In CREATE FUNCTION statement? Possible must be:
> >>
> >> select name1, name2 from foo() where name1 > 10;
> >
> > Yes, optimal would imho also be if the foo() somehow had access to the
> > where restriction, so it could only produce output, that the
> > higher level is interested in, very cool. This would be extremely
> > useful for me. Very hard to implement, or even find an appropriate
> > interface for though.
>
> You could easily implement it *in* the function foo IMHO. Since the
> function does some black magic to create the result set to begin with, you
> can change it to use parameters:
>
> select name1, name2 from foo(10, NULL, NULL) where name1 > 10;
The function execution (data reading, etc) is almost last thing in the
path-of-query. The parser, planner and others parts of PG must already
knows enough information about a "relation" foo(). I don't know how much
is intimate idea about this (Tom?), but somewhere in the pg_class /
pg_attribute must be something about foo() result. (*IMHO* of course:)
I can't imagine that foo() builts on-the-fly arbitrary attributes.
By the way, what permissions? For select (view) we can do GRANT/REVOKE,
and for select * from foo()? For standard tables it's in the
pg_class.relacl. IMHO solution is add foo() to pg_class and mark here
oid of function foo() from pg_proc, and attributes definition store
to pg_attribute -- everything as for standard table. The source for
this information must be from CREATE FUNCTION statement, like:
CREATE FUNCTION foo RETURNS( name1 int, name2 text) ....;
If the foo is in the pg_class you can do "GRANT ... ON foo";
Karel
-- Karel Zak <zakkr@zf.jcu.cz>http://home.zf.jcu.cz/~zakkr/C, PostgreSQL, PHP, WWW, http://docs.linux.cz,
http://mape.jcu.cz
On Wed, 27 Jun 2001, Karel Zak wrote: > On Wed, Jun 27, 2001 at 10:56:43AM +0200, Reinoud van Leeuwen wrote: > > > > > >> For the result from foo() you must somewhere define attributes > > >> (names). > > >> Where? In CREATE FUNCTION statement? Possible must be: > > >> > > >> select name1, name2 from foo() where name1 > 10; > > > > > > Yes, optimal would imho also be if the foo() somehow had access to the > > > where restriction, so it could only produce output, that the > > > higher level is interested in, very cool. This would be extremely > > > useful for me. Very hard to implement, or even find an appropriate > > > interface for though. > > > > You could easily implement it *in* the function foo IMHO. Since the > > function does some black magic to create the result set to begin with, you > > can change it to use parameters: > > > > select name1, name2 from foo(10, NULL, NULL) where name1 > 10; > > The function execution (data reading, etc) is almost last thing in the > path-of-query. The parser, planner and others parts of PG must already > knows enough information about a "relation" foo(). I don't know how much > is intimate idea about this (Tom?), but somewhere in the pg_class / > pg_attribute must be something about foo() result. (*IMHO* of course:) > > I can't imagine that foo() builts on-the-fly arbitrary attributes. > > By the way, what permissions? For select (view) we can do GRANT/REVOKE, > and for select * from foo()? For standard tables it's in the > pg_class.relacl. IMHO solution is add foo() to pg_class and mark here > oid of function foo() from pg_proc, and attributes definition store > to pg_attribute -- everything as for standard table. The source for > this information must be from CREATE FUNCTION statement, like: > > CREATE FUNCTION foo RETURNS( name1 int, name2 text) ....; > > If the foo is in the pg_class you can do "GRANT ... ON foo"; I'm planning to require return type to be a existing pg_type already. The problem with your idea is question if you have two functions (for example) foo(timestamp) and foo(int4), you must embed the types into relname, and that's ugly. Once its possible to control permission to execute a function via GRANT, it solves the grant problem for function-as-tablesource -alex
On Wed, Jun 27, 2001 at 06:54:27AM -0400, Alex Pilosov wrote:
> On Wed, 27 Jun 2001, Karel Zak wrote:
>
> > On Wed, Jun 27, 2001 at 10:56:43AM +0200, Reinoud van Leeuwen wrote:
> > > >
> > > >> For the result from foo() you must somewhere define attributes
> > > >> (names).
> > > >> Where? In CREATE FUNCTION statement? Possible must be:
> > > >>
> > > >> select name1, name2 from foo() where name1 > 10;
> > > >
> > > > Yes, optimal would imho also be if the foo() somehow had access to the
> > > > where restriction, so it could only produce output, that the
> > > > higher level is interested in, very cool. This would be extremely
> > > > useful for me. Very hard to implement, or even find an appropriate
> > > > interface for though.
> > >
> > > You could easily implement it *in* the function foo IMHO. Since the
> > > function does some black magic to create the result set to begin with, you
> > > can change it to use parameters:
> > >
> > > select name1, name2 from foo(10, NULL, NULL) where name1 > 10;
> >
> > The function execution (data reading, etc) is almost last thing in the
> > path-of-query. The parser, planner and others parts of PG must already
> > knows enough information about a "relation" foo(). I don't know how much
> > is intimate idea about this (Tom?), but somewhere in the pg_class /
> > pg_attribute must be something about foo() result. (*IMHO* of course:)
> >
> > I can't imagine that foo() builts on-the-fly arbitrary attributes.
> >
> > By the way, what permissions? For select (view) we can do GRANT/REVOKE,
> > and for select * from foo()? For standard tables it's in the
> > pg_class.relacl. IMHO solution is add foo() to pg_class and mark here
> > oid of function foo() from pg_proc, and attributes definition store
> > to pg_attribute -- everything as for standard table. The source for
> > this information must be from CREATE FUNCTION statement, like:
> >
> > CREATE FUNCTION foo RETURNS( name1 int, name2 text) ....;
> >
> > If the foo is in the pg_class you can do "GRANT ... ON foo";
>
> I'm planning to require return type to be a existing pg_type already. The
Sure, nobody wants to works with something other than is in the
pg_type.
> problem with your idea is question if you have two functions (for example)
> foo(timestamp) and foo(int4), you must embed the types into relname, and
> that's ugly.
Good point. First, you needn't work with types, bacause function oid
is unique for foo(timestamp) and foo(int4). You can work with function
oid. But this is not important.
The important thing is that in the PostgreSQL is already resolved very
simular problem. We can define function with same names, unique must
be function_name + arguments_types. Why not add same thing for tables and
allows to define as unique table_name + table_type (where table_type
is 'standard table', 'foo() table' and in future may be some other
special type of table). The parser detect type of table very easy -- 'foo' vs. 'foo()'.
IMHO very important is how add new feature and use it together with
old feature.
> Once its possible to control permission to execute a function via GRANT,
> it solves the grant problem for function-as-tablesourceThe permissions system was an example only. If you add
"foo()-tables"
as something what needs special usage and care you probably found more
problems. For example, what show command '\d' in the psql client, how
relation show pg_access ..etc?
Karel
-- Karel Zak <zakkr@zf.jcu.cz>http://home.zf.jcu.cz/~zakkr/C, PostgreSQL, PHP, WWW, http://docs.linux.cz,
http://mape.jcu.cz
On Wed, 27 Jun 2001, Karel Zak wrote: > Sure, nobody wants to works with something other than is in the > pg_type. > > > problem with your idea is question if you have two functions (for example) > > foo(timestamp) and foo(int4), you must embed the types into relname, and > > that's ugly. > > Good point. First, you needn't work with types, bacause function oid > is unique for foo(timestamp) and foo(int4). You can work with function > oid. But this is not important. That's not nice. GRANT ALL ON FOO_231234 where 231234 is OID of foo(int4)? ew. > The important thing is that in the PostgreSQL is already resolved very > simular problem. We can define function with same names, unique must > be function_name + arguments_types. Why not add same thing for tables and > allows to define as unique table_name + table_type (where table_type > is 'standard table', 'foo() table' and in future may be some other > special type of table). > The parser detect type of table very easy -- 'foo' vs. 'foo()'. This is a little bit better, but, results in following syntax: GRANT SELECT ON FOO(int4). I'm not sure if this really makes sense. Its not a select permission, its an execute permission on a function, and should be handled when/where execute permission is checked. Its not hard to implement (just change what parser thinks relation is), but I'm sure will conflict with _something_. > IMHO very important is how add new feature and use it together with > old feature. > > > Once its possible to control permission to execute a function via GRANT, > > it solves the grant problem for function-as-tablesource > > The permissions system was an example only. If you add "foo()-tables" > as something what needs special usage and care you probably found more > problems. For example, what show command '\d' in the psql client, how > relation show pg_access ..etc? \df Its a function, not a relation. You can do a lot of things to a relation (such as define rules, triggers, constraints), which do not make any sense for a function. The function may be used as a table-source, but it does not make it a table. If you can give me a better example than permissions system, I'll surely reconsider, but currently, I see no use for it... -alex
On Wed, Jun 27, 2001 at 08:42:07AM -0400, Alex Pilosov wrote:
> On Wed, 27 Jun 2001, Karel Zak wrote:
> This is a little bit better, but, results in following syntax:
> GRANT SELECT ON FOO(int4). I'm not sure if this really makes sense. Its
> not a select permission, its an execute permission on a function, and
And if we will have select permission for columns?
> should be handled when/where execute permission is checked.
>
> Its not hard to implement (just change what parser thinks relation is),
> but I'm sure will conflict with _something_.
>
> > IMHO very important is how add new feature and use it together with
> > old feature.
> >
> > > Once its possible to control permission to execute a function via GRANT,
> > > it solves the grant problem for function-as-tablesource
> >
> > The permissions system was an example only. If you add "foo()-tables"
> > as something what needs special usage and care you probably found more
> > problems. For example, what show command '\d' in the psql client, how
> > relation show pg_access ..etc?
> \df
And list of attributes of foo()?
> Its a function, not a relation. You can do a lot of things to a relation
> (such as define rules, triggers, constraints), which do not make any sense
Say with me: it isn't a function, its a function that returning records
and we will use it in same possition as standard table only. The other
usage donsn't exist for this.
I want wring out from foo()-tables most what is possible (like
permissions, rules, views). IMHO it's correct requirement :-)
Karel
-- Karel Zak <zakkr@zf.jcu.cz>http://home.zf.jcu.cz/~zakkr/C, PostgreSQL, PHP, WWW, http://docs.linux.cz,
http://mape.jcu.cz
On Wed, 27 Jun 2001, Karel Zak wrote: > On Wed, Jun 27, 2001 at 08:42:07AM -0400, Alex Pilosov wrote: > > On Wed, 27 Jun 2001, Karel Zak wrote: > > > This is a little bit better, but, results in following syntax: > > GRANT SELECT ON FOO(int4). I'm not sure if this really makes sense. Its > > not a select permission, its an execute permission on a function, and > > And if we will have select permission for columns? Function returns a tuple. To me, it really makes no sense "this user can see this attribute of a tuple, but not the other one". > > > > > > The permissions system was an example only. If you add "foo()-tables" > > > as something what needs special usage and care you probably found more > > > problems. For example, what show command '\d' in the psql client, how > > > relation show pg_access ..etc? > > \df > > And list of attributes of foo()? Foo returns type x. \dt x. > > > Its a function, not a relation. You can do a lot of things to a relation > > (such as define rules, triggers, constraints), which do not make any sense > > Say with me: it isn't a function, its a function that returning records > and we will use it in same possition as standard table only. The other > usage donsn't exist for this. > > I want wring out from foo()-tables most what is possible (like > permissions, rules, views). IMHO it's correct requirement :-) permissions -- see above rules -- how? 'create rule blah on select from foo(int4) do instead select from baz()'? Sorry, that's just too strange for me :) views -- why not. Create view bar as select * from foo() [1] Actually, now that I think about it, your idea is essentially creation of a view automatically when the function returning setof record is created. I don't think its a good idea. If you really want to pretend its a table/view, then create such a view [1]. -alex