I am trying to create `crosstab` queries in PostgreSQL such that it automatically generates the `crosstab` columns instead of hardcoding it. I have written a function that dynamically generates the column list that I need for my `crosstab` query. The idea is to substitute the result of this function in the `crosstab` query using dynamic sql.

I know how to do this easily in SQL Server, but my limited knowledge of PostgreSQL is hindering my progress here. I was thinking of storing the result of function that generates the dynamic list of columns into a variable and use that to dynamically build the sql query. It would be great if someone could guide me regarding the same.

```

-- Table which has be pivoted
CREATE TABLE test_db
(
    kernel_id int,
    key int,
    value int
);

INSERT INTO test_db VALUES
(1,1,99),
(1,2,78),
(2,1,66),
(3,1,44),
(3,2,55),
(3,3,89);

-- This function dynamically returns the list of columns for crosstab
CREATE FUNCTION test() RETURNS TEXT AS '
DECLARE
    key_id int;
    text_op TEXT = '' kernel_id int, '';
BEGIN
    FOR key_id IN SELECT DISTINCT key FROM test_db ORDER BY key LOOP
    text_op := text_op || key_id || '' int , '' ;
    END LOOP;
    text_op := text_op || '' DUMMY text'';
    RETURN text_op;
END;
' LANGUAGE 'plpgsql';

-- This query works. I just need to convert the static list
-- of crosstab columns to be generated dynamically.
SELECT * FROM
crosstab
(
    'SELECT kernel_id, key, value FROM test_db ORDER BY 1,2',
    'SELECT DISTINCT key FROM test_db ORDER BY 1'
)
AS x (kernel_id int, key1 int, key2 int, key3 int); -- How can I replace ..
-- .. this static list with a dynamically generated list of columns ?

```