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https://issues.apache.org/jira/browse/HIVE-2928?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13250786#comment-13250786
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Mithun Radhakrishnan commented on HIVE-2928:
--------------------------------------------
@Carl: Thank you for the pointer.
Would your suggestion be that changing the datatype in Hive's pacakge.jdo won't
be acceptable because there might be deployments with MySQL with JDO
column-validations turned on?
> Support for Oracle-backed Hive-Metastore ("longvarchar" to "clob" in
> package.jdo)
> ---------------------------------------------------------------------------------
>
> Key: HIVE-2928
> URL: https://issues.apache.org/jira/browse/HIVE-2928
> Project: Hive
> Issue Type: New Feature
> Components: Metastore
> Affects Versions: 0.9.0
> Reporter: Mithun Radhakrishnan
> Attachments: HIVE-2928.patch
>
>
> I'm trying to get the Hive-Metastore to work when backed by an Oracle
> backend. There's a change to hive's package.jdo that I'd like advice/comments
> on.
> One sticking point on working with Oracle has been the TBLS table (MTable)
> and its 2 LONGVARCHAR properties (VIEW_ORIGINAL_TEXT and VIEW_EXPANDED_TEXT).
> Oracle doesn't support more than one LONGVARCHAR property per table (for
> reason of legacy), and prefers that one use CLOBs instead. If one switches to
> CLOB properties, with no modification to hive's package.jdo, one sees the
> following exception:
> <quote>
> Incompatible data type for column TBLS.VIEW_EXPANDED_TEXT : was CLOB
> (datastore), but type expected was LONGVARCHAR (metadata). Please check that
> the type in the datastore and the type specified in the MetaData are
> consistent.
> org.datanucleus.store.rdbms.exceptions.IncompatibleDataTypeException:
> Incompatible data type for column TBLS.VIEW_EXPANDED_TEXT : was CLOB
> (datastore), but type expected was LONGVARCHAR (metadata). Please check that
> the type in the datastore and the type specified in the MetaData are
> consistent.
> at
> org.datanucleus.store.rdbms.table.ColumnImpl.validate(ColumnImpl.java:521)
> at
> org.datanucleus.store.rdbms.table.TableImpl.validateColumns(TableImpl.java:2
> </quote>
> But if one rebuilds Hive with the package.jdo changed to use CLOBs instead of
> LONGVARCHARs, things look promising:
> 1. The exception no longer occurs. Things seem to work with Oracle. (I've yet
> to scale-test.)
> 2. These modified hive-libraries work as is with pre-existing mysql
> metastores. Migrating data isn't a worry.
> 3. The unit-tests seem to run through.
> Would there be opposition to changing the package.jdo's LONGVARCHAR
> references to CLOB, if this works with mysql and with Oracle?
> Mithun
> P.S. I also have a working hive-schema-0.9.0-oracle.sql script that I'm
> testing, for the related issue of creating the required tables in Oracle.
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