2017-08-11 21:04:04 -04:00
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CREATE EXTENSION lo;
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CREATE TABLE image (title text, raster lo);
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CREATE TRIGGER t_raster BEFORE UPDATE OR DELETE ON image
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FOR EACH ROW EXECUTE PROCEDURE lo_manage(raster);
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SELECT lo_create(43213);
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SELECT lo_create(43214);
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INSERT INTO image (title, raster) VALUES ('beautiful image', 43213);
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SELECT lo_get(43213);
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SELECT lo_get(43214);
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UPDATE image SET raster = 43214 WHERE title = 'beautiful image';
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SELECT lo_get(43213);
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SELECT lo_get(43214);
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2020-03-09 09:22:22 +01:00
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-- test updating of unrelated column
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UPDATE image SET title = 'beautiful picture' WHERE title = 'beautiful image';
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SELECT lo_get(43214);
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2017-08-11 21:04:04 -04:00
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DELETE FROM image;
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SELECT lo_get(43214);
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Repair incorrect handling of AfterTriggerSharedData.ats_modifiedcols.
This patch fixes two distinct errors that both ultimately trace
to commit 71d60e2aa, which added the ats_modifiedcols field.
The more severe error is that ats_modifiedcols wasn't accounted for
in afterTriggerAddEvent's scanning loop that looks for a pre-existing
duplicate AfterTriggerSharedData. Thus, a new event could be
incorrectly matched to an AfterTriggerSharedData that has a different
value of ats_modifiedcols, resulting in the wrong tg_updatedcols
bitmap getting passed to the trigger whenever it finally gets fired.
We'd not noticed because (a) few triggers consult tg_updatedcols,
and (b) we had no tests exercising a case where such a trigger was
called as an AFTER trigger. In the test case added by this commit,
contrib/lo's trigger fails to remove a large object when expected
because (without this fix) it thinks the LO OID column hasn't changed.
The other problem was introduced by commit ce5aaea8c, which copied the
modified-columns bitmap into trigger-related storage. It made a copy
for every trigger event, whereas what we really want is to make a new
copy only when we make a new AfterTriggerSharedData entry. (We could
imagine adding extra logic to reduce the number of bitmap copies still
more, but it doesn't look worthwhile at the moment.) In a simple test
of an UPDATE of 10000000 rows with a single AFTER trigger, this thinko
roughly tripled the amount of memory consumed by the pending-triggers
data structures, from 160446744 to 480443440 bytes.
Fixing the first problem requires introducing a bms_equal() call into
afterTriggerAddEvent's scanning loop, which is slightly annoying from
a speed perspective. However, getting rid of the excessive bms_copy()
calls from the second problem balances that out; overall speed of
trigger operations is the same or slightly better, in my tests.
Discussion: https://postgr.es/m/3496294.1737501591@sss.pgh.pa.us
Backpatch-through: 13
2025-01-22 11:58:20 -05:00
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-- Now let's try it with an AFTER trigger
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DROP TRIGGER t_raster ON image;
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CREATE CONSTRAINT TRIGGER t_raster AFTER UPDATE OR DELETE ON image
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DEFERRABLE INITIALLY DEFERRED
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FOR EACH ROW EXECUTE PROCEDURE lo_manage(raster);
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SELECT lo_create(43223);
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SELECT lo_create(43224);
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SELECT lo_create(43225);
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INSERT INTO image (title, raster) VALUES ('beautiful image', 43223);
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SELECT lo_get(43223);
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UPDATE image SET raster = 43224 WHERE title = 'beautiful image';
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SELECT lo_get(43223); -- gone
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SELECT lo_get(43224);
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-- test updating of unrelated column
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UPDATE image SET title = 'beautiful picture' WHERE title = 'beautiful image';
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SELECT lo_get(43224);
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-- this case used to be buggy
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BEGIN;
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UPDATE image SET title = 'beautiful image' WHERE title = 'beautiful picture';
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UPDATE image SET raster = 43225 WHERE title = 'beautiful image';
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SELECT lo_get(43224);
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COMMIT;
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SELECT lo_get(43224); -- gone
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SELECT lo_get(43225);
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DELETE FROM image;
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SELECT lo_get(43225); -- gone
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2024-11-14 12:24:00 +09:00
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SELECT lo_oid(1::lo);
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2017-08-11 21:04:04 -04:00
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DROP TABLE image;
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