Re: Large Object to Bytea Conversion

Hi,

Le mardi 14 novembre 2006 14:36, Markus Schiltknecht a écrit :
> I want to convert some large objects to bytea fields on the server.
> Searching through the documentation didn't reveal any hints. Am I
> missing something or is there really no such thing as a
> lo_convert_to_bytea function?

You may want to try this code given on IRC by i-can't-remember-who:

CREATE FUNCTION _phpads_agg_concat (bytea, bytea) RETURNS bytea AS $_$SELECT
$1 || $2$_$ LANGUAGE sql IMMUTABLE STRICT;
CREATE AGGREGATE phpads_agg_concat (bytea) (SFUNC = _phpads_agg_concat, STYPE
= bytea, INITCOND = '');

EXPLAIN ANALYZE SELECT phpads_agg_concat(data) FROM (SELECT data FROM
pg_largeobject WHERE loid = 24513361 ORDEY BY pageno) t;
                                                                      QUERY
PLAN

-------------------------------------------------------------------------------------------------------------------------------------------------------
 Aggregate  (cost=10.62..10.63 rows=1 width=32) (actual time=4.682..4.685
rows=1 loops=1)
   ->  Index Scan using pg_largeobject_loid_pn_index on pg_largeobject
(cost=0.00..10.57 rows=4 width=1863) (actual time=0.075..0.162 rows=4
loops=1)
         Index Cond: (loid = 24513361::oid)
 Total runtime: 5.146 ms


CREATE FUNCTION phppgads_lo_readall(oid) RETURNS bytea AS $_$SELECT
phpads_agg_concat(data) FROM (SELECT data FROM pg_largeobject WHERE loid = $1
ORDEY BY pageno) t$_$ LANGUAGE sql STRICT;


Hope this will help,
--
Dimitri Fontaine
http://www.dalibo.com/