Re: How to dereference 2 dimensional array?

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От Bartosz Dmytrak
Тема Re: How to dereference 2 dimensional array?
Дата
Msg-id CAD8_UcbidqGWe=1nNT5vawHktVWV8Xd+6JM7tHBkCUkBN=p3=A@mail.gmail.com
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Ответ на How to dereference 2 dimensional array?  (ChoonSoo Park <luispark@gmail.com>)
Список pgsql-general
Hi,
this could be start point for discussion:


CREATE OR REPLACE FUNCTION public."arraysToHstore" (IN a TEXT[], OUT c hstore[])
RETURNS hstore[]
AS
$BODY$
DECLARE 
i INT;
elements INT;
dim INT;
BEGIN
elements := array_length(a,2); -- # of elements in each dimension
dim := array_length(a,1); -- # of dimensions
a := string_to_array(array_to_string(a, '|', 'NULL'), '|', 'NULL'); --rewrite multidimensional array into single dimensional

FOR i IN 0..(dim -1) LOOP --loop throug all dimensions to create hsore array (0 is for first elment in rewrited array)
c[i+1] = hstore (a[(i*elements)+1: (i+1)*elements]); --create hstore array element using part of array "a", this part (window) is moving while loop is evaluated)
END LOOP;

END
$BODY$
LANGUAGE plpgsql SECURITY DEFINER IMMUTABLE STRICT;

--usage example
SELECT (public."arraysToHstore"('{{"f1", "1", "f3", "123", "f4", "ABC"}, {"f5", "2", "f6", "345", "f7", "DEF"}}')::hstore[])[2]

This works for me (PostgreSQL 9.1.2).
You can pass whatever text array You want (any size, but 2 dimensions only) and You will receive 1 dimentional hstore array with number of elements corresponding to input array's dimensions)

Regards,
Bartek


2012/2/16 ChoonSoo Park <luispark@gmail.com>

I would like to construct hstore array from 2 dimensional array.


For example, 


'{{f1, 1, f2, 123, f3, ABC, ...}, {f1, 2, f2, 345, f3, DEF, ...}}'


Should be converted to


2 hstore values

"f1"=>"1", "f2"=>"123", "f3"=>"ABC", ...

"f2"=>"2", "f2"=>"345", "f3"=>"DEF", ...


create or replace function convertHStore(p1 text[][]) RETURNS hstore[]


hstore function requires text[] to convert array to hstore. Therefore I should be able to dereference 2 dimensional array element.

Inside this custom plpgsql function, p1[1] is not valid syntax to dereference the 1st element in p1.


Anyone knows how to solve this problem?


Thank you,

Choon Park 


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