Re: [Pytables-users] error creating table with many columns

[Francesc A. <fa...@ca...>]

Hi Stefan,

A Dimarts 04 Octubre 2005 20:12, Stefan Kuzminski va escriure:
> I am getting an error creating a table with 1000+ columns, the error is
>
>
>   #005: H5O.c line 2157 in H5O_new_mesg(): object header message is too
> large (16k max)
>
> the full error message is below, is there a limit on the number of
> columns  I can put in a table?

I've never checked the creation of tables so wide, but, looking at the
error, this effectively seems a limitation of the underlying HDF5
library on the size of the headers of datasets (which is 16k, as you
see). I don't know if this limitation can be surmounted in some way,
but I'd recommend you to do not surpass a reasonable limit for columns
(maybe 256 or 512 as maximum). You can use multidimensional columns if
you don't have enough with the recommended maximum.

[Perhaps it would be nice to issue a warning when user is trying to
exceed 256 or 512 columns.]

> There error also implies there is a
> limit to the size of the attributes on a table?

Yes, I think so. Generally speaking you should use attributes to add
metadata information that is small in size. If you try to use metainfo
that is bigger than, say, 1k, you should put it on a dedicated leave
(*Array or Table).

Cheers,

=2D-=20
>0,0<   Francesc Altet =A0 =A0 http://www.carabos.com/
V   V   C=E1rabos Coop. V. =A0=A0Enjoy Data
 "-"