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From Dain Sundstrom <d...@iq80.com>
Subject Type length, scale, and precision?
Date Tue, 19 Mar 2019 20:30:54 GMT
For the types in the ORC footer, we have the following:

 // the maximum length of the type for varchar or char in UTF-8 characters
 optional uint32 maximumLength = 4;
 // the precision and scale for decimal
 optional uint32 precision = 5;
 optional uint32 scale = 6;

If the maximumLength, is set to N, can I be confident that no value for that column in the
file will contain more than N UTF-8 characters?  Is this still true for concatenated ORC files.

I have a similar question about DECIMAL.  Decimal encoding currently uses the SECONDARY stream
to encode the "scale".  Is this scale guaranteed to be the same scale as the type scale in
the footer?

Thanks,

-dain


----
Dain Sundstrom
Co-founder @ Presto Software Foundation, Co-creator of Presto (https://prestosql.io)


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