Re: 9.3.9 and pg_multixact corruption

[ adding Bjorn Munch to Cc ]

Jim Nasby writes:
> On 9/20/15 9:23 AM, Christoph Berg wrote:
>> a short update here: the customer updated the compiler to a newer
>> version, is now compiling using -O2 instead of -O3, and the code
>> generated now looks sane, so this turned out to be a compiler issue.
>> (Though it's unclear if the upgrade fixed it, or the different -O
>> level.)
>
> Do we officially not support anything > -O2? If so it'd be nice if
> configure threw at least a warning (if not an error that you had to
> explicitly over-ride).

At least the solaris binaries distributed via postgresql.org[1] have
been compiled with -xO3 according to pg_config.  And their code for
multixact.c looks inconspicuous.  To recap the data points:

| compiler                                          | flags | multixact.o |
|---------------------------------------------------+-------+-------------|
| Sun C 5.12 SunOS_sparc Patch 148917-07 2013/10/18 | -xO3  | bad         |
| Sun C 5.13 SunOS_Sparc 2014/10/20                 | -xO2  | good        |
| Sun C 5.8 Patch 121015-04 2007/01/10              | -xO3  | good        |

regards,
Andreas

Footnotes: 
[1]  http://www.postgresql.org/download/solaris/