Re: Concatenating bytea types...

On 28/02/13 10:21, Marko Rihtar wrote:
> Hi all,
>
> i have a little problem.
> I'm trying to rewrite one procedure from mysql that involves bytes
> concatenation.
> This is my snippet from postgres code:

You seem to be mixing up escape and hex literal formatting along with
decode(). The following should help.

BEGIN;

CREATE FUNCTION to_hex_pair(int) RETURNS text AS $$
SELECT right('0' || to_hex($1), 2);
$$ LANGUAGE sql;

CREATE FUNCTION f_concat_bytea1(bytea, bytea) RETURNS text AS $$
BEGIN
RETURN $1 || $2;
END;
$$ LANGUAGE plpgsql;

CREATE FUNCTION f_concat_bytea2(bytea, bytea) RETURNS bytea AS $$
DECLARE
cv1 bytea;
BEGIN
cv1 := '\x01'::bytea;
RETURN $1 || cv1 || $2;
END;
$$ LANGUAGE plpgsql;

CREATE FUNCTION f_concat_bytea3(text, text) RETURNS bytea AS $$
DECLARE
cv1 text;
BEGIN
cv1 := '01';
RETURN decode($1 || cv1 || $2, 'hex');
END;
$$ LANGUAGE plpgsql;

SELECT '\x000b'::bytea AS want_this,
decode('000b','hex') AS or_this1,
decode('\000\013','escape') AS or_this2;
SELECT f_concat_bytea1('\x00', '\x0b');
SELECT f_concat_bytea2('\x00', '\x0b');
SELECT f_concat_bytea3('00', '0b');

ROLLBACK;

--
Richard Huxton
Archonet Ltd