Thread: If there a bug in the psql or just a feature .

Dear all,

I'm currently working on my thesis and I chose psql. What I need to do
is defining a new type in psql.

It should be dynamic array.

| 1 | 2 | 3.0 | 4.5 | 2.1 |  . .. . .


// This one is not working
typedef struct Myindex {double *indexes;int level;int size;
} Myindex

Myindex *
Myindex_in {

}

Myindex *
Myindex_out {However when I try to get back the data. It seems that the lastinsertion always overwrite other previous
insertion.Inparticular, it overwrites all data from 2nd to n-1th record.where n is the number of insertion but not the
firstone.
 
}


// This one work ok but the idea is to have dynamic array.
// This would defeat the purpose of this new structure.

typedef struct Myindex {       double indexes[10];       int level;       int size;
} Myindex;


Standalone debuging works for both cases.
However psql accepts only the static array.


Could anybody enlight me on this issue, please


regards,
Van

Vanmunin Chea <vac@cse.unsw.EDU.AU> writes:
> // This one is not working
> typedef struct Myindex {
>     double *indexes;
>     int level;
>     int size;
> } Myindex

You cannot use a pointer inside a Postgres datatype.  The system will
have no idea that the pointer is there and so will not copy the
pointed-to data, nor update the pointer, when the datum is copied,
stored on disk, etc.
        regards, tom lane

Hey Tom,
Thanks for the tips, Tom. I have that feeling from the start
(with the two different implementation) but never actually have a chance
to confirm with someone.

1. It there a way to store the dynamic array at all ?

I notice psql has a similar type - Single Dynamic Dimensional
Array. However there isn't any built in operators(<,<=,==,>,>=) for Array
to do sorting.

2. Can I write one up ?


regards,
Van.



On Tue, 10 Sep 2002, Tom Lane wrote:

> Vanmunin Chea <vac@cse.unsw.EDU.AU> writes:
> > // This one is not working
> > typedef struct Myindex {
> >     double *indexes;
> >     int level;
> >     int size;
> > } Myindex
>
> You cannot use a pointer inside a Postgres datatype.  The system will
> have no idea that the pointer is there and so will not copy the
> pointed-to data, nor update the pointer, when the datum is copied,
> stored on disk, etc.
>
>             regards, tom lane
>

Vanmunin Chea

On Tue, 2002-09-10 at 17:22, Vanmunin Chea wrote:
> Hey Tom,
>
>     Thanks for the tips, Tom. I have that feeling from the start
> (with the two different implementation) but never actually have a chance
> to confirm with someone.
>
> 1. It there a way to store the dynamic array at all ?
>
>
>     I notice psql has a similar type - Single Dynamic Dimensional
> Array. However there isn't any built in operators(<,<=,==,>,>=) for Array
> to do sorting.
>
> 2. Can I write one up ?

See attachment.

Unfortunately I ran out of time before figuring out how to make btree
index use it ;(

Also, in 7.3 there are a lot more ops for in contrib/intarray than was
in 7.2.

-------------
Hannu