Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

Hi, I don't think it would be worth to keep a separate NaN count, but we could ignore them when calculating min/max stats regardless. However, NaN is not the only value preventing total ordering. We could have a similar problem with not finding +0.0 values because a -0.0 is written to the

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

There is an extensibility mechanism with the ColumnOrder union - I think that was meant to avoid the need to add new stat fields? Given that the bug was in the Parquet spec, we'll need to make a spec change anyway, so we could add a new ColumnOrder - FloatingPointTotalOrder? at the same time as

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

I hope the common cases is that data files do not contain these special float values. As the simplest solution, how about writers refrain from populating the stats if a special value is encountered? That fix does not preclude a more thorough solution in the future, but it addresses the common

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

> We could have a similar problem > with not finding +0.0 values because a -0.0 is written to the max_value > field by some component that considers them the same. My hope is that the filtering would behave sanely, since -0.0 == +0.0 under the real-number-inspired ordering, which is distinguished

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

On Fri, Feb 16, 2018 at 9:15 AM, Tim Armstrong wrote: > I don't see a major benefit to a temporary solution. The files are already > out there and we need to implement a fix on the read path regardless. If we > keep writing the stats there's at least some information

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

On Fri, Feb 16, 2018 at 9:38 AM, Tim Armstrong wrote: > The reader still can't correctly interpret those stats without knowing > about the behaviour of that specific writer though, because it can't assume > the absence of NaNs unless it knows that they are reading a file

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

I don't see a major benefit to a temporary solution. The files are already out there and we need to implement a fix on the read path regardless. If we keep writing the stats there's at least some information contained in the stats that readers can make use of, if they want to implement the

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

Yeah, I missed that. We set it per column, so all other types could keep TypeDefinedOrder and floats could have something like NanAwareDoubleOrder. On Fri, Feb 16, 2018 at 9:18 AM, Tim Armstrong wrote: > We wouldn't need to rev the whole TypeDefinedOrder thing right?

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

I think one idea behind the column order fields was that if a reader does not recognize a value there, it needs to ignore the stats. If I remember correctly, that was intended to allow us to add new orderings for collations, but it also seems useful to address gaps in the spec or known broken

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

We wouldn't need to rev the whole TypeDefinedOrder thing right? Couldn't we just define a special order for floats? Essentially it would be a tag for writers to say "hey I know about this total order thing". On Fri, Feb 16, 2018 at 9:14 AM, Lars Volker wrote: > I think one

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

The reader still can't correctly interpret those stats without knowing about the behaviour of that specific writer though, because it can't assume the absence of NaNs unless it knows that they are reading a file written by a writer that drops stats when it sees NaNs. It *could* fix the behaviour

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

I would just like to mention that the fmax() / fmin() functions in C/C++ Math library follow the aforementioned IEEE 754-2008 min and max specification: http://en.cppreference.com/w/c/numeric/math/fmax I think this behavior is also the most intuitive and useful regarding to statistics. If we want

Re: Inconsistent float/double sort order in spec and implementations can lead to incorrect results

On Fri, Feb 16, 2018 at 9:44 AM, Zoltan Borok-Nagy wrote: > I would just like to mention that the fmax() / fmin() functions in C/C++ > Math library follow the aforementioned IEEE 754-2008 min and max > specification: > http://en.cppreference.com/w/c/numeric/math/fmax > >