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ea68ea6320
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
74 lines
1.6 KiB
PL/PgSQL
74 lines
1.6 KiB
PL/PgSQL
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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-- 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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DELETE FROM image;
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SELECT lo_get(43214);
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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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SELECT lo_oid(1::lo);
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DROP TABLE image;
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