Hi list, Back in June we had a discussion about parsing denormal floating-point values. A float8->text conversion could result in a number that can't be converted back to float8 anymore for some values. Among other things, this could break backups (though my searches didn't turn up any reports of this ever happening).
The reason is that Linux strtod() sets errno=ERANGE for denormal numbers. This behavior is also explicitly allowed (implementation-defined) by the C99 standard. Further analysis was done by Jeroen Vermeulen here: http://archives.postgresql.org/pgsql-hackers/2011-06/msg01773.php I think the least invasive fix, as proposed by Jeroen, is to fail only when ERANGE is set *and* the return value is 0.0 or +/-HUGE_VAL. Reading relevant specifications, this seems to be a fairly safe assumption. That's what the attached patch does. (I also updated the float4in function, but that's not strictly necessary -- it would fail later in CHECKFLOATVAL() anyway) What I don't know is how many platforms are actually capable of parsing denormal double values. I added some regression tests, it would be interesting to see results from pgbuildfarm and potentially revert these tests later. Regards, Marti -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
