On Fri, Dec 15, 2023 at 2:00 PM Alexander Lakhin <exclusion@gmail.com> wrote:
Your patch looks good to me, but maybe you would find it suitable to fix in passing one more integer overflow in costsize.c?
Concretely, the query: CREATE TABLE t(id int PRIMARY KEY, i int); EXPLAIN (VERBOSE) UPDATE t SET i = ni FROM (SELECT g id, 1 ni FROM generate_series(1, 2147483648) g) s WHERE t.id = s.id;
when executed with ubsan-enabled build, gives: costsize.c:1017:12: runtime error: 2.14748e+09 is outside the range of representable values of type 'int' #0 0x5603325818e0 in cost_bitmap_heap_scan .../src/backend/optimizer/path/costsize.c:1017:12 #1 0x5603326cc519 in create_bitmap_heap_path .../src/backend/optimizer/util/pathnode.c:1065:2
Nice catch. The overflow occurs when cost_bitmap_heap_scan() calls compute_bitmap_pages(), and the loop_count parameter is converted from double to int. I wonder if we can change the loop_count parameter to be double for compute_bitmap_pages() to avoid such overflow.
