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From "Sushanth Sowmyan (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-6166) JsonSerDe is too strict about table schema
Date Wed, 08 Jan 2014 14:59:51 GMT
Sushanth Sowmyan created HIVE-6166:
--------------------------------------

             Summary: JsonSerDe is too strict about table schema
                 Key: HIVE-6166
                 URL: https://issues.apache.org/jira/browse/HIVE-6166
             Project: Hive
          Issue Type: Bug
          Components: HCatalog, Serializers/Deserializers
    Affects Versions: 0.12.0
            Reporter: Sushanth Sowmyan
            Assignee: Sushanth Sowmyan


JsonSerDe is too strict when it comes to schema, erroring out if it finds a subfield with
a key name that does not map to an appropriate type/schema of a table, or an inner-struct
schema.

Thus, if a schema specifies "s:struct<a:int,b:string>,k:int" and we pass it data that
looks like the following:

{noformat}
{ "x" : "abc" , "s" : { "a" : 2 , "b" : "blah", "c": "woo" } }
{noformat}

This should still pass, and the record should be read as if it were 

{noformat}
{ "s" : { "a" : 2 , "b" : "blah"}, k :  null }
{noformat}

This will allow the JsonSerDe to be used with a wider set of data where the data does not
map too finely to the declared table schema.

Note, we are still strict about a couple of things:

a) If there is a declared schema column, then the type cannot vary, that is still considered
an error. i.e., if the hive table schema says k1 is a boolean, it cannot magically change
into an int or a struct, say, for eg.
b) The JsonSerDe still attempts to map hive internal column names - i.e. if the data contains
a column named "_col2", then, if "_col2" is not declared directly in the schema, it will map
to column position 2 in that schema/subschema, rather than ignoring the field. This is so
that tables created with CTAS will still work. 



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