PostgreSQL对数组的遍历

create table test_array(id serial primary key, str1 int[][][]);


插入两条测试数据。
insert into test_array values (1,array[[[1,2],[3,4],[5,6]],[[20,30],[40,50],[70,100]]]);
insert into test_array values (2,array[[[100,200],[300,400],[500,600]],[[2000,3000],[4000,5000],[7000,10000]]]);

为了能直观的看到结果集，我们得把数组的值换成普通的类型拿出来， 有以下几种方法。

create or replace function sp_array2table_simple(
anyarray
)
returns table (element int) as
$ytt$
declare array1 alias for $1;
	x int;
begin
  drop table if exists tmp_1;
  create temporary table tmp_1 (id int);
  
  <> foreach x  in array array1
  loop
    insert into tmp_1 values (x);
  end loop label1;
  
  return query select * from tmp_1;
end;
$ytt$ language plpgsql;


t_girl=#select sp_array2table_simple(str1) as array_list from test_array where id = 2;


 array_list
------------
        100
        200
        300
        400
        500
        600
       2000
       3000
       4000
       5000
       7000
      10000
(12 行记录)

时间：7.780 ms

create or replace function sp_array2table(
anyarray
)
returns table (element int) as
$ytt$
declare array1 alias for $1;
	x int[];
	nlen int := 0;
	i int := 1;	
begin
  drop table if exists tmp_1;
  create temporary table tmp_1 (id int);
  
  <> foreach x slice 1 in array array1
    loop
      nlen := array_length(x,1);
      i := 1;
      <> while i <= nlen loop
        insert into tmp_1 values (x[i]);
        i := i + 1;
      end loop label2;
  end loop label1;
  
  return query select * from tmp_1;
end;
$ytt$ language plpgsql;


t_girl=#select sp_array2table(str1) as array_list from test_array where id = 2;


 array_list
------------
        100
        200
        300
        400
        500
        600
       2000
       3000
       4000
       5000
       7000
      10000
(12 行记录)

时间：20.139 ms

t_girl=#select  regexp_split_to_table(array_to_string(str1,','),',+') as array_list from test_array where id = 2;

 array_list
------------
 100
 200
 300
 400
 500
 600
 2000
 3000
 4000
 5000
 7000
 10000
(12 行记录)

时间：0.850 ms