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8520174b4e
This oversight could result in a tuplestore using much more than the intended amount of memory. It would only happen in a code path that loaded a tuplestore via tuplestore_putvalues(), and many of those won't emit huge amounts of data; but cases such as holdable cursors and plpgsql's RETURN NEXT command could have the problem. The fix ensures that the tuplestore will switch to write-to-disk mode when it overruns work_mem. The potential overrun was finite, because we would still count the space used by the tuple pointer array, so the tuplestore code would eventually flip into write-to-disk mode anyway. When storing wide tuples we would go far past the expected work_mem usage before that happened; but this may account for the lack of prior reports. Back-patch to 8.4, where tuplestore_putvalues was introduced. Per bug #6061 from Yann Delorme.