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From paul-rogers <...@git.apache.org>
Subject [GitHub] drill issue #594: DRILL-4842: SELECT * on JSON data results in NumberFormatE...
Date Sun, 19 Feb 2017 00:54:43 GMT
Github user paul-rogers commented on the issue:

    https://github.com/apache/drill/pull/594
  
    We have three cases for nulls:
    
    1. See a typed field, followed by nulls. Here, we know the type, just mark the current
field as null.
    2. Run of nulls at start of file, followed by a non-null value within the same record
batch. We can transform the null field into a typed field. That is what this fix tries to
do.
    3. Run of nulls in one record batch, followed by a non-null value in the next batch. This
must trigger a schema change. The question is, does it trigger based on adding a new field,
or assuming a type in the first batch, then changing the type in the second?
    
    The code presumably handles the first case. Case 3 is beyond the scope of this fix. So,
the question is, how best to handle the second case? Is the present fix sufficient?


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