Re: user defined data types - help - Mailing list pgsql-general

Because of 2 reaons:

1. My C structure consists of other such fields like 'latency' etc. Here I
have shown 'bandwidth' for the ease of explaining. Having tables for each
such field will lead to large number of tables and hence will soon get
unmanageable.

2. I have a table in which I want to have this structure as one field.

Thanks.

On Sat, 14 Sep 2002, Martijn van Oosterhout wrote:

> Why are you trying to store this all into one value? Why not just create two
> tables, one for the names of the machines and one to stores the bandwidths?
>
> On Fri, Sep 13, 2002 at 11:39:23AM -0400, Sathish Vadhiyar wrote:
> >
> > Hi.
> >
> > I have a struct in C in my application program.
> >
> > typedef struct{
> >   int count;
> >   char** machine_names;
> >   double* bandwidth;
> > } MACHINEINFO;
> >
> > 'count' is the number of machines. machine_names[i] gives the machine name
> > of machine i. 'bandwidth' is a matrix that stores bandwidth information
> > between the machines. So bandwidth[i*count+j] gives the bandwidth between
> > machines i and j.
> >
> > Iam trying to define a corresponding structure and define the type to
> > store in a postgresql datat base using 'CREATE TYPE'.
> >
> > I don't want to have a structure like
> >
> > typedef struct{
> >   int32 size; /* for variable length */
> >   int4 count;
> >   char data[1];
> > } PSQLSTRUCT;
> >
> > and have both the machine_names and bandwidth encoded into string stored
> > in 'data'.
> >
> > What I would like instead is something like a 'polygon' type where I would
> > have.
> >
> > typedef struct{
> >   char machine_name[100]; /* Ideally, I don't want to fix the size of a
> >                              single machine as 100. But I will compromise
> >                              for the moment  */
> >   float8 bandwidth; /* ???? */
> > } SINGLEMACHINE
> >
> > typedef struct{
> >   int32 size;
> >   int4 count;
> >   SINGLEMACHINE sm[1]; /* variable number of machines */
> > } PSQLSTRUCT;
> >
> > This is similar to the POLYGON built in type where the structure polygon
> > consists of variable number of POINT structures.
> >
> > But here is the tricky issue. Unlike the POINT structure that contains
> > fileds of fixed lengths, my SINGLEMACHINE structure consists of variable
> > length field in 'bandwidth'.
> >
> > Any ideas regarding how to do this?
> >
> >
> > Thanks.
> >
> > ---------------------------------------------------------------------
> >
> > Sathish S. Vadhiyar
> > PhD Candidate   Research Assistant, Innovative Computing Laboratory
> > Computer Science Department
> > University of Tennessee
> > Knoxville
> >
> > Ph: (865)946-4558 (H) , (865)974-6323 (O).
> >
> >
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>
> --
> Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> > There are 10 kinds of people in the world, those that can do binary
> > arithmetic and those that can't.
>
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>


---------------------------------------------------------------------

Sathish S. Vadhiyar
PhD Candidate   Research Assistant, Innovative Computing Laboratory
Computer Science Department
University of Tennessee
Knoxville

Ph: (865)946-4558 (H) , (865)974-6323 (O).