Hi Ayush, Thanks for the review.
On Wed, Jun 10, 2026 at 7:09 PM Ayush Tiwari <[email protected]> wrote: > On Wed, 10 Jun 2026 at 14:02, Amit Langote <[email protected]> wrote >> Thanks for checking. I will review them a bit more closely before >> committing by Friday. Other reviews are welcome. > > Thanks for the patch! > > I read through v1-0001 and v1-0002 and tried them locally. I had a couple of > things I wanted to ask about. > > 1. The per-entry "flushing" flag and test coverage. If I'm reading the two > patches together correctly, with both applied the 64-row re-entry test in 0001 > reaches the flush through ri_FastPathEndBatch(), where 0002's cache-wide > ri_fastpath_flushing guard already routes the re-entrant check to the per-row > path before it gets back into ri_FastPathBatchAdd(). Does that mean the > per-entry flag from 0001 isn't really exercised by that test once 0002 is in? > As far as I can tell you'd need the flush to fire from ri_FastPathBatchAdd() > itself (a 65th row) to reach it. I tried a 65-row variant (same FK, > re-entrant > DML from the cast during the full-batch flush), including a case where the > re-entrant row was an orphan, and it seemed to do the right thing; the > per-row fallback still raised the violation. Would it be worth switching the > test to 65 rows, or adding that variant, so the per-entry guard is covered > too? > Or am I missing a path where the committed test already hits it? You're right. With 0002 applied, the 64-row test reaches the flush through ri_FastPathEndBatch(), where the cache-wide ri_fastpath_flushing guard catches the re-entry before it returns to ri_FastPathBatchAdd(), so the per-entry flag is no longer exercised by that test. To hit the per-entry flag the flush has to fire from ri_FastPathBatchAdd() itself, which the 64-row case no longer does once the add and flush are reordered. Rather than bump the test to 65 rows, I'd prefer to keep the flush firing from ri_FastPathBatchAdd() at 64 by not reordering the add and flush, and prevent the OOB write by bounds-checking the write instead, as done in the attached updated 0001. A re-entrant add then can't overrun the array regardless of the flag, the per-entry flushing guard still routes the re-entry to the per-row path, and a 64-row statement flushes from ri_FastPathBatchAdd() on the 64th row, so the existing test exercises the per-entry guard. > 2. Resetting ri_fastpath_flushing. I noticed it's cleared only in the > PG_FINALLY of ri_FastPathEndBatch(), which does seem to cover the cases I > could > think of. Since ri_FastPathXactCallback already NULLs ri_fastpath_cache and > clears ri_fastpath_callback_registered at transaction end, I wondered whether > it might be worth clearing ri_fastpath_flushing there too, just as cheap > insurance against some future path that leaves it set across transactions > though maybe that's unnecessary given the PG_FINALLY. Agreed, it's cheap and matches the existing resets there, so I've added it to ri_FastPathXactCallback() in v2-0002. > Other than the above queries, the patch looks good to me. Updated patches attached. -- Thanks, Amit Langote
v2-0001-Fix-out-of-bounds-write-in-RI-fast-path-batch-on-.patch
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v2-0002-Confine-RI-fast-path-batching-to-the-top-transact.patch
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