Re: general purpose array_sort

On Thu, Oct 24, 2024 at 8:40 PM jian he <jian(dot)universality(at)gmail(dot)com> wrote:
>
> On Wed, Oct 23, 2024 at 10:28 PM Junwang Zhao <zhjwpku(at)gmail(dot)com> wrote:
> > PFA v7 with multi-array support.
> >
>
> if (ARR_NDIM(array) == 1)
> {
> }
> else
> {
> }
> can be simplified.
> i think beginning part of array_sort can be like the following:
> (newline emitted)
>
> ---------------------------------------------------------------------
> if (ARR_NDIM(array) < 1)
> PG_RETURN_ARRAYTYPE_P(array);
> if (dirstr != NULL)
> {
> if (!parse_sort_order(text_to_cstring(dirstr), &sort_asc, &nulls_first))
> ereport(ERROR,
> (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> errmsg("second parameter must be a valid sort
> direction")));
> }
> elmtyp = ARR_ELEMTYPE(array);
> if (ARR_NDIM(array) > 1)
> elmtyp = get_array_type(elmtyp);

I'm wondering should we cache the type entry for both element type and
the corresponding array type, for example if we have a table:

create table t(b int[]);
insert into t values ('{1,3}'),('{{2,3}}'),('{{1,2},{0,2}}');

with 1-d array and m-d array interleaved, then the following query will
call lookup_type_cache multiple times.

select array_sort((t.b)) from t;

> typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
> if (typentry == NULL || typentry->type_id != elmtyp)
> {
> typentry = lookup_type_cache(elmtyp, sort_asc ?
> TYPECACHE_LT_OPR : TYPECACHE_GT_OPR);
> if ((sort_asc && !OidIsValid(typentry->lt_opr)) ||
> (!sort_asc && !OidIsValid(typentry->gt_opr)))
> ereport(ERROR,
> (errcode(ERRCODE_UNDEFINED_FUNCTION),
> errmsg("could not identify an ordering operator
> for type %s",
> format_type_be(elmtyp))));
> fcinfo->flinfo->fn_extra = (void *) typentry;
> }
> ---------------------------------------------------------------------
> /*
> * array_sort
> *
> * Sorts the array in either ascending or descending order.
> * The array must be empty or one-dimensional.
> */
> comments need to be updated.

will fix it in the next version of patch.

>
>
> typedef enum
> PARSE_SORT_ORDER_DONE
> } ParseSortOrderState;
>
> last one, should have comma, like
> "PARSE_SORT_ORDER_DONE, "

will fix it.

--
Regards
Junwang Zhao