Hive should expand nested structs when setting the table schema from thrift
structs
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Key: HIVE-2941
URL: https://issues.apache.org/jira/browse/HIVE-2941
Project: Hive
Issue Type: Bug
Reporter: Travis Crawford
Assignee: Travis Crawford
When setting a table serde, the deserializer is queried for its schema, which
is used to set the metastore table schema. The current implementation uses the
class name stored in the field as the field type.
By storing the class name as the field type, users cannot see the contents of a
struct with "describe tblname". Applications that query HiveMetaStore for the
table schema (specifically HCatalog in this case) see an unknown field type,
rather than a struct containing known field types.
Hive should store the expanded schema in the metastore so users browsing the
schema see expanded fields, and applications querying metastore see familiar
types.
DETAILS
Set the table serde to something like this. This serde uses the built-in
{{ThriftStructObjectInspector}}.
{code}
alter table foo_test
set serde "com.twitter.elephantbird.hive.serde.ThriftSerDe"
with serdeproperties ("serialization.class"="com.foo.Foo");
{code}
This causes a call to {{MetaStoreUtils.getFieldsFromDeserializer}} which
returns a list of fields and their schemas. However, currently it does not
handle nested structs, and if {{com.foo.Foo}} above contains a field
{{com.foo.Bar}}, the class name {{com.foo.Bar}} would appear as the field type.
Instead, nested structs should be expanded.
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