Re: BUG #19405: Assertion in eval_windowaggregates() fails due to integer overflow

On Fri, Feb 13, 2026 at 7:09 PM PG Bug reporting form
<noreply@postgresql.org> wrote:
> The following script:
> CREATE TABLE t (i integer);
> INSERT INTO t SELECT g FROM generate_series(1, 2) g;
> SELECT SUM(i) OVER (ROWS BETWEEN 1 PRECEDING AND 0x7fffffffffffffff
> FOLLOWING EXCLUDE CURRENT ROW) FROM t;

Thanks for the report.  Reproduced here.

It seems to be caused by a signed integer overflow in row_is_in_frame
when calculating the frame's end position:

            if (pos > winstate->currentpos + offset)
                return -1;

When offset is very large (close to INT64_MAX, as in the reported
case), the addition can overflow, in which case the result would wrap
to a negative number (with -fwrapv), causing the comparison to
incorrectly return true.  In release builds, this causes valid rows to
be excluded from the window frame.  In debug builds, it leads to an
assertion failure.

I think we can fix this by leveraging the overflow-aware integer
operation (ie, pg_add_s64_overflow) to perform the addition here.  If
an overflow is detected, we can assume the frame boundary extends to
the end of the partition, meaning the current row is within the frame.

- Richard