4 Commits

Author SHA1 Message Date
Tom Lane
ea68ea6320 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
Michael Paquier
3ef038fc4f contrib/lo: Add test for function lo_oid()
Author: Ronan Dunklau
Discussion: https://postgr.es/m/ZzMSJkiNZhimjXWx@paquier.xyz
2024-11-14 12:24:00 +09:00
Peter Eisentraut
71d60e2aa0 Add tg_updatedcols to TriggerData
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
2020-03-09 09:34:55 +01:00
Peter Eisentraut
4cb89d8306 lo: Add test suite
Reviewed-by: David Steele <david@pgmasters.net>
2017-09-14 22:22:59 -04:00