Re: MetaData (size of datatype)

On Mon, 2002-04-29 at 13:16, Shra wrote:
> Hi Hannu,
>
> > -1 is given for types that are of fixed size and whose length can be
> > read from pg_type.typlen for that type.
>
> I don't think so...jsut look into this file pq_type.h.... it says.........
> *****************************************************************
> typlen is the number of bytes we use to represent a value of this type, e.g.
> 4 for an int4. But for a variable length type, typlen is -1
> *****************************************************************
>
> -1 is for variable length n not for fixed length.........this point is very
> clear even in documentation..........

Yes, it in pg_type.typlen it is -1 is for variable length and actual
length for fixed-length types

in pg_attribute.attypmod it is -1 for _fixed_ length types and actual
length for variable length types (actual length = defined length + 4
bytes of length bytes)

> now how to find length for a numeric, varchar or anyother one that has
> variable length where the system PQfsize returns -1.........?
>
> As tom said.....The type is encoded in the atttypmod field (see PQfmod) and
> recommended using format_type().....
> but when this is used, it returns -1 for integer , real n other fixed
> datatypes .........

so do as Tom said -

if
PQfsize returns -1
then
use PQfmod
else
use PQfsize

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