Tom Lane wrote:
Mark Kirkwood <[EMAIL PROTECTED]> writes:

I thought I would have a look at:
(Datatypes) Add function to return compressed length of TOAST data values.

My recollection of that discussion is that we just wanted something
that would return the actual VARSIZE() of the datum.  You're building
something way too confusing ...

I was guessing a little about exactly what was wanted - for some reason I couldn't access the mail archives for the last few days (however, can now).

A more interesting point is that the way you've declared the function,
it will only work on text values, which is pretty limiting.  Ideally
we'd define this thing as "pg_datum_length(any-varlena-type) returns int"
but there is no pseudotype corresponding to "any varlena type".

I was thinking about this the other day in connection with my proposal
to make something that could return the TOAST value OID of an
out-of-line datum.  I think the only non-restrictive way to do it would
be to declare the function as taking "any", and then add a runtime check
using the get_fn_expr_argtype() mechanism to test that what you've been
given is in fact a varlena datatype.

Yes - was thinking I needed to check if the Datum was a varlena (and didn't know how to do it...), so thanks for the pointer!

With these thoughts in mind, I'll have another go :-)



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