[jira] [Updated] (PARQUET-1222) Definition of float and double sort order is ambiguous

["Julien Le Dem (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PARQUET-1222?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Julien Le Dem updated PARQUET-1222:
-----------------------------------
    Summary: Definition of float and double sort order is ambiguous  (was: Definition of float and double sort order is ambigious)

> Definition of float and double sort order is ambiguous
> ------------------------------------------------------
>
>                 Key: PARQUET-1222
>                 URL: https://issues.apache.org/jira/browse/PARQUET-1222
>             Project: Parquet
>          Issue Type: Bug
>          Components: parquet-format
>            Reporter: Zoltan Ivanfi
>            Priority: Critical
>             Fix For: format-2.5.0
>
>
> Currently parquet-format specifies the sort order for floating point numbers as follows:
> {code:java}
>    *   FLOAT - signed comparison of the represented value
>    *   DOUBLE - signed comparison of the represented value
> {code}
> The problem is that the comparison of floating point numbers is only a partial ordering with strange behaviour in specific corner cases. For example, according to IEEE 754, -0 is neither less nor more than \+0 and comparing NaN to anything always returns false. This ordering is not suitable for statistics. Additionally, the Java implementation already uses a different (total) ordering that handles these cases correctly but differently than the C\+\+ implementations, which leads to interoperability problems.
> TypeDefinedOrder for doubles and floats should be deprecated and a new TotalFloatingPointOrder should be introduced. The default for writing doubles and floats would be the new TotalFloatingPointOrder. This ordering should be effective and easy to implement in all programming languages.
> For reading existing stats created using TypeDefinedOrder, the following compatibility rules should be applied:
> * When looking for NaN values, min and max should be ignored.
> * If the min is a NaN, it should be ignored.
> * If the max is a NaN, it should be ignored.
> * If the min is \+0, the row group may contain -0 values as well.
> * If the max is -0, the row group may contain \+0 values as well.



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