Re: head fails to build on SLES 12 (wal_compression=zstd)

On Thu, Mar 31, 2022 at 11:44 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Justin Pryzby <pryzby(at)telsasoft(dot)com> writes:
> > Possible responses look like:
> > - Use 0 which also means "default" (need to verify that works across versions);
> > - Or #ifndef ZSTD_CLEVEL_DEFAULT #define ZSTD_CLEVEL_DEFAULT 3;
> > - Add a test for a minimum zstd version v1.3.7. This may be a good idea for
> > v15 in any case, since we're using a few different APIs (at least
> > ZSTD_compress and ZSTD_compressStream2 and execve(zstd)).
>
> In view of 51c0d186d ("Allow parallel zstd compression"), I agree
> that some clarity about the minimum supported version of zstd
> seems essential. I don't want to be dealing with threading bugs
> in ancient zstd versions. However, why do you suggest 1.3.7 in
> particular?

One thing to note is that apparently threading wasn't enabled in the
default build before 1.5.0, which was released in May 2021, but it did
exist as an option in the code for some period of time prior to that.
I don't know how long exactly. I don't want to jump to the conclusion
that other people's old versions are full of bugs, but if that should
happen to be true here, there's some chance that PostgreSQL users
won't be exposed to them just because threading wasn't enabled by
default until quite recently.

--
Robert Haas
EDB: http://www.enterprisedb.com