Re: general purpose array_sort

On Sat, Sep 28, 2024 at 7:52 PM Junwang Zhao <zhjwpku@gmail.com> wrote:
>
> PFA v2, use COLLATE keyword to supply the collation suggested by
> Andreas offlist.
>
this is better. otherwise we need extra care to handle case like:
SELECT array_sort('{1,3,5,2,4,6}'::int[] COLLATE "pg_c_utf8");


+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>array_sort</primary>
+        </indexterm>
+        <function>array_sort</function> ( <type>anyarray</type>
<optional>, <parameter>dir</parameter> </optional>)
+        <returnvalue>anyarray</returnvalue>
+       </para>
+       <para>
+        Sorts the array in either ascending or descending order.
+        <parameter>dir</parameter> must be <literal>asc</literal>
+        or <literal>desc</literal>. The array must be empty or one-dimensional.
+       </para>
+       <para>
+        <literal>array_sort(ARRAY[1,2,5,6,3,4])</literal>
+        <returnvalue>{1,2,3,4,5,6}</returnvalue>
+       </para></entry>
+      </row>
I am confused with <parameter>dir</parameter>. I guess you want to say
"direction"
But here, I think <parameter>sort_asc</parameter> would be more appropriate?


<parameter>dir</parameter> can have only two potential values, make it
as a boolean would be more easier?
you didn't mention information:  "by default, it will sort by
ascending order; the sort collation by default is using the array
element type's collation"

tuplesort_begin_datum can do null-first, null-last, so the
one-dimension array can allow null values.

Based on the above and others, I did some refactoring, feel free to take it.
my changes, changed the function signature, so you need to pay
attention to sql test file.