Re: BLOB support

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> Friday 03 of June 2011 18:08:56
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > On Thu, Jun 2, 2011 at 12:53 PM, Radosław Smogura
> >
> > <rsmogura(at)softperience(dot)eu> wrote:
> >> 1. No tracking of unused LO (you store just id of such object). You may
> >> leak LO after row remove/update. User may write triggers for this, but
> >> it is not argument - BLOB type is popular, and it's simplicity of use
> >> is quite important. When I create app this is worst thing.
> >>
> >> 2. No support for casting in UPDATE/INSERT. So there is no way to simple
> >> migrate data (e.g. from too long varchars). Or to copy BLOBs.
> >>
> >> 3. Limitation of field size to 1GB.
> >
> > As a general point, it would probably be a good idea to address each
> > of these issues separately, and to have a separate discussion about
> > each one.
> >
> > As to #1 specifically, if you use a text or bytea field rather than a
> > large object per se, then this issue goes away. But then you lose the
> > streaming functionality. So at least some people here are saying that
> > we should try to fix that by adding the streaming functionality to
> > text/bytea rather than by doing anything to the large object facility.
>
> #2 is also a problem that only becomes a problem if you insist that LOBs
> have to be a distinct kind of value.
>
> regards, tom lane

And one more topic to discuss. Should blob be referencable, e.g. I create in
JDBC new Blob, I set stream for it what should happen if I will call
UPDATE t set b = ? where 1=1
?

This is not about copy on write.

Regards,
Radek