mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-07-14 05:09:18 +02:00
71d60e2aa0
This allows a trigger function to determine for an UPDATE trigger which columns were actually updated. This allows some optimizations in generic trigger functions such as lo_manage and tsvector_update_trigger. Reviewed-by: Daniel Gustafsson <daniel@yesql.se> Discussion: https://www.postgresql.org/message-id/flat/11c5f156-67a9-0fb5-8200-2a8018eb2e0c@2ndquadrant.com
51 lines
940 B
Plaintext
51 lines
940 B
Plaintext
CREATE EXTENSION lo;
|
|
CREATE TABLE image (title text, raster lo);
|
|
CREATE TRIGGER t_raster BEFORE UPDATE OR DELETE ON image
|
|
FOR EACH ROW EXECUTE PROCEDURE lo_manage(raster);
|
|
SELECT lo_create(43213);
|
|
lo_create
|
|
-----------
|
|
43213
|
|
(1 row)
|
|
|
|
SELECT lo_create(43214);
|
|
lo_create
|
|
-----------
|
|
43214
|
|
(1 row)
|
|
|
|
INSERT INTO image (title, raster) VALUES ('beautiful image', 43213);
|
|
SELECT lo_get(43213);
|
|
lo_get
|
|
--------
|
|
\x
|
|
(1 row)
|
|
|
|
SELECT lo_get(43214);
|
|
lo_get
|
|
--------
|
|
\x
|
|
(1 row)
|
|
|
|
UPDATE image SET raster = 43214 WHERE title = 'beautiful image';
|
|
SELECT lo_get(43213);
|
|
ERROR: large object 43213 does not exist
|
|
SELECT lo_get(43214);
|
|
lo_get
|
|
--------
|
|
\x
|
|
(1 row)
|
|
|
|
-- test updating of unrelated column
|
|
UPDATE image SET title = 'beautiful picture' WHERE title = 'beautiful image';
|
|
SELECT lo_get(43214);
|
|
lo_get
|
|
--------
|
|
\x
|
|
(1 row)
|
|
|
|
DELETE FROM image;
|
|
SELECT lo_get(43214);
|
|
ERROR: large object 43214 does not exist
|
|
DROP TABLE image;
|