Re: array support patch phase 1 patch

Joe Conway kirjutas T, 08.04.2003 kell 19:55:
> Hannu Krosing wrote:
> > SELECT ARRAY[1,2] < ARRAY[1,2,3]; # --> FALSE
> >
> > Support for sorting and b-tree indexing could be nice too.
>
> I thought briefly about this, but it wasn't immediately clear what the
> semantics ought to be in all cases. I've also spent literally all my
> available "hacking" time for the last several weeks just to get to the
> patch submitted. I'd like to see at least some of it committed before I
> take on anything new ;-)
>
> If you want to propose in detail how these would behave - including:

I like the "compare like strings" approach

> - different length arrays

shorter is smaller if all elements are same

> - different dimension arrays

not comparable, just as array elemant is not comparable with array

> - is comparison by ordinal position, or is each element compared to
> all elements of the other side,

neither, pairs of elements at same positions are compared until first !=
or one array ends, then the shorter array the array with smaller element
value is considered smaller.

> e.g. is
> (ARRAY[1,2,3] < ARRAY[2,3,4]) TRUE or FALSE?
> If you compare by ordinal position TRUE, but in the latter case
> FALSE

all the following should also be TRUE

(ARRAY[1,2,3] < ARRAY[2,1,1])
(ARRAY[1,2,3] < ARRAY[1,2,3,4])
(ARRAY[] < ARRAY[1,2,3,4])
(ARRAY[1,2,3,4] < ARRAY[1,2,4,3])

> > Where should one start to add PL/Python support for polymorphic types ?
>
> Not entirely sure. In plperl, pltcl, and plr there is a section of code
> in the compile function that looks something like:
>
> ....

Thanks, I'll take a look.

> > What about moving contrib/intagg into backend ?
> > (And converting it into ANYagg on the way ;)
> >
>
> As I said earlier, all in good time ;-) One question about that though
> -- how is intagg different from array_accum? (which is already
> polymorphic and in the submitted patch)

Sorry, didn't notice array_accum.

intagg has functions for doing it both ways (array->table and table ->
array).

-----------------
Hannu