Sushanth Sowmyan created HIVE-6166:
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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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