On Wed, Mar 18, 2026 at 4:36 PM Lukas Fittl <[email protected]> wrote: > On Wed, Mar 18, 2026 at 1:49 PM Zsolt Parragi <[email protected]> > wrote: > > There seems to be one more bug in this: > > > > 1. EXPLAIN ANALYZE fires a trigger > > 2. The trigger function throws ERROR, InstrStopTrigger never runs > > 3. ResOwnerReleaseInstrumentation runs but only checks > > unfinalized_children, not triggers > > 4. InstrStopFinalize discards the trigger entry > > 5. Trigger instrumentation information shows 0 > > Hmm, so I think you're correct that a trigger function error would > cause any stack-based instrumentation from the trigger to get lost. > > In practice that doesn't matter today, since triggers never capture > WAL/buffer usage data (only timing),
After twisting and turning this in my head more, I realize that's actually not correct - as it stands, trigger instrumentation is inheriting the instrumentation options from the overall query, and so that will cause a typical EXPLAIN (ANALYZE) to also capture Buffer/WAL usage for triggers - it just won't be shown in EXPLAIN. Since its not used in practice, we could fix that by explicitly setting INSTRUMENT_TIMER for triggers, but AFAIR Andres had noted on a prior iteration that special casing this doesn't seem right, since we should probably output buffer/WAL usage for triggers anyway. So I guess that brings us back to, we should fix it with one of the ways I mentioned. FWIW, I was able to create a test case in the pg_session_buffer_usage module to that effect, so there is indeed a current issue where activity during triggers gets lost and won't be added to the overall totals on abort. Thanks, Lukas -- Lukas Fittl
