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From wgtmac <...@git.apache.org>
Subject [GitHub] orc pull request #116: ORC-185: [C++] Simplify Statististics Implementation
Date Tue, 02 May 2017 23:14:09 GMT
Github user wgtmac commented on a diff in the pull request:

    https://github.com/apache/orc/pull/116#discussion_r114446720
  
    --- Diff: c++/src/Statistics.hh ---
    @@ -41,49 +41,181 @@ namespace orc {
       };
     
     /**
    + * Internal Statistics Implementation
    + */
    +
    +  template <typename T>
    --- End diff --
    
    We may need some functions like void increase(uint64 count) to increase valueCount. I
can add them when needed. 
    My main concern for using templates is that we need to compare, update, merge ColumnStatistics,
and transform to protobuf version for implementing writers and using templates will also introduce
some duplicate code. It means we still need to do template specialization for different types
like Date, Timestamp, Decimal, etc. if we want to let class ColumnStatistics to handle the
update (e.g. use ColumnStatistics<T>::update(T value) to update min/max for type T).
Otherwise we may need to let specific ColumnWriters to be responsible for update (e.g. DecimalColumnWriter
to compare min/max of decimal values and then use setMax/setMin of ColumnStatistics<Decimal>
to update the values).


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