PostgreSQL supports arrays, but does not have a function to sort internal data elements. Today I wrote one with PLPGSQL and PLPYTHONU respectively.
Example Table Structure:
t_girl=# \d test_array; Table "ytt.test_array" Column | Type | Modifiers --------+-----------+--------------------------------------------------------- id | integer | not null default nextval('test_array_id_seq'::regclass) str1 | integer[] | Indexes: "test_array_pkey" PRIMARY KEY, btree (id)
Sample Data:
t_girl=# select * from test_array; id | str1 ----+--------------------------- 1 | {100,200,300,5,10,20,100} 2 | {200,100,2,30,0,5} 3 | {2000,101,2,30,0,10}(3 rows)Time: 1.513 ms
Plsql storage function array_sort execution result:
Ascending
t_girl=# select id,array_sort(str1,'asc') from test_array; id | array_sort ----+--------------------------- 1 | {5,10,20,100,100,200,300} 2 | {0,2,5,30,100,200} 3 | {0,2,10,30,101,2000}(3 rows)Time: 2.377 ms
Descending Order
t_girl=# select id,array_sort(str1,'desc') from test_array; id | array_sort ----+--------------------------- 1 | {300,200,100,100,20,10,5} 2 | {200,100,30,5,2,0} 3 | {2000,101,30,10,2,0}(3 rows)Time: 3.318 mst_girl=#
Python storage function array_sort_python execution result:
Descending order:
t_girl=# select id,array_sort_python(str1,'desc') from test_array; id | array_sort_python ----+--------------------------- 1 | {300,200,100,100,20,10,5} 2 | {200,100,30,5,2,0} 3 | {2000,101,30,10,2,0}(3 rows)
Time: 2.797 ms
Ascending Order:
t_girl=# select id,array_sort_python(str1,'asc') from test_array; id | array_sort_python ----+--------------------------- 1 | {5,10,20,100,100,200,300} 2 | {0,2,5,30,100,200} 3 | {0,2,10,30,101,2000}(3 rows)Time: 1.856 mst_girl=#
Appendix: array_sort_python code:
CREATE or replace FUNCTION array_sort_python(c1 text [],f_order text) RETURNS text [] AS $$result = []if f_order.lower() == 'asc': c1.sort() result = c1elif f_order.lower() == 'desc': c1.sort(reverse=True) result = c1else: passreturn result$$ LANGUAGE plpythonu;
Array_sort code:
create or replace function array_sort(anyarray,f_order text) returns anyarray as $ytt$declare array1 alias for $1; tmp int; result text [];begin if lower(f_order) = 'desc' then for tmp in select unnest(array1) as a order by a desc loop result := array_append(result,tmp::text); end loop; return result; elsif lower(f_order) = 'asc' then for tmp in select unnest(array1) as a order by a asc loop result := array_append(result,tmp::text); end loop; return result; else return array['f_order must be asc or desc!']; end if;end;$ytt$ language plpgsql;