Re: text datum VARDATA and strings

On Mon, 2006-08-14 at 15:51 -0400, Tom Lane wrote:

> Whose 7.x manual? This stuff has been there since we invented the
> "version 1" function call convention, which was 7.3 or before. There
> is some documentation in the SGML docs, but really we kind of expect you
> to look at the standard built-in functions to see how things are done...

The PostgreSQL manual. I wrote these functions early in the 7.x series
and I don't know which manual version exactly. For example, the sec
9.5.4 of
http://www.postgresql.org/docs/7.3/static/xfunc-c.html shows code for
concat_text, which I remember was the basis for what I wrote. I now see
and understand the text regarding detoasting the 'DatumGetXXX' macros;
the relevance of these were not obvious to me at the time.

> So it's best not to assume that you know what is inside a
> text datum, if possible,

Okay. Does that mean that code in 9.5.4 should have a warning to that
effect?

> > 3) Is there any reason to believe that the code below is problematic?
>
> The only thing I'd suggest is that checking for a null return from
> palloc is a waste of effort. It doesn't return to you if it runs
> out of memory.

Okay. Thanks for the advice, Tom.

-Reece

--
Reece Hart, http://harts.net/reece/, GPG:0x25EC91A0