Re: Fixed length data types issue

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Tom Lane wrote:
> >> Either way, I think it would be interesting to consider
> >>
> >> (a) length word either one or two bytes, not four. You can't need more
> >> than 2 bytes for a datum that fits in a disk page ...
>
> > That is an interesting observation, though could compressed inline
> > values exceed two bytes?
>
> After expansion, perhaps, but it's the on-disk footprint that concerns
> us here.

I'm a bit confused by this and how it would be handled in your sketch. I
assumed we needed a bit pattern dedicated to 4-byte length headers because
even though it would never occur on disk it would be necessary to for the
uncompressed and/or detoasted data.

In your scheme what would PG_GETARG_TEXT() give you if the data was detoasted
to larger than 16k?

--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com