Re: [PATCH] Fix crash in int8_avg_combine().

On Sat, Nov 25, 2017 at 10:55 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> I believe we already dealt with this:
>
> Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> Branch: REL_10_STABLE [619a8c47d] 2017-11-14 17:49:49 -0500
> Branch: REL9_6_STABLE [4a15f87d2] 2017-11-14 17:49:49 -0500
> Branch: REL9_5_STABLE [d4e38489f] 2017-11-14 17:49:49 -0500
>
> Prevent int128 from requiring more than MAXALIGN alignment.
>
> Our initial work with int128 neglected alignment considerations, an
> oversight that came back to bite us in bug #14897 from Vincent
> Lachenal.
> It is unsurprising that int128 might have a 16-byte alignment
> requirement;
> what's slightly more surprising is that even notoriously lax Intel
> chips
> sometimes enforce that.
>
> Raising MAXALIGN seems out of the question: the costs in wasted disk
> and
> memory space would be significant, and there would also be an on-disk
> compatibility break. Nor does it seem very practical to try to allow
> some
> data structures to have more-than-MAXALIGN alignment requirement, as
> we'd
> have to push knowledge of that throughout various code that copies data
> structures around.
>
> The only way out of the box is to make type int128 conform to the
> system's
> alignment assumptions. Fortunately, gcc supports that via its
> __attribute__(aligned()) pragma; and since we don't currently support
> int128 on non-gcc-workalike compilers, we shouldn't be losing any
> platform
> support this way.
>
> Although we could have just done pg_attribute_aligned(MAXIMUM_ALIGNOF)
> and
> called it a day, I did a little bit of extra work to make the code more
> portable than that: it will also support int128 on compilers without
> __attribute__(aligned()), if the native alignment of their 128-bit-int
> type is no more than that of int64.
>
> Add a regression test case that exercises the one known instance of the
> problem, in parallel aggregation over a bigint column.
>
> Back-patch of commit 751804998. The code known to be affected only
> exists
> in 9.6 and later, but we do have some stuff using int128 in 9.5, so
> patch
> back to 9.5.
>
> Discussion: https://postgr.es/m/20171110185747.31519.28038@
> wrigleys.postgresql.org
>
> Does that solution not work for you?
>

It works for me. My REL_10_STABLE was out of date. A git pull fixed it.