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https://issues.apache.org/jira/browse/HIVE-28909?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhihua Deng updated HIVE-28909:
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Component/s: Standalone Metastore
> After DataNucleus upgrade to 6.0.8 for JDK17 compatibility, there are
> unnecessary update queries executing by DN
> ----------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-28909
> URL: https://issues.apache.org/jira/browse/HIVE-28909
> Project: Hive
> Issue Type: Bug
> Components: Standalone Metastore
> Reporter: Kokila N
> Assignee: Sai Hemanth Gantasala
> Priority: Major
> Labels: pull-request-available
> Fix For: 4.1.0
>
>
> For Hive with JDK17 compile support, Data-Nucleus needed to be upgraded from
> 5.x to 6.x
> After upgrading to 6.x (specifically version 6.0.8), we observed multiple
> QTest failures, particularly for SELECT queries due to unexpected UPDATE
> statements being triggered on the COLUMNS_V2 table during read operations.
> {code:java}
> Caused by: org.apache.hadoop.hive.metastore.api.MetaException:
> JDOUserException: One or more instances could not be retrieved
> Root cause: Error : 22848, Position : 102, Sql = UPDATE COLUMNS_V2 SET
> "COMMENT" = :1 WHERE CD_ID=:2 AND "COMMENT" = :3 AND "COLUMN_NAME" = :4 AND
> TYPE_NAME = :5,
> OriginalSql = UPDATE COLUMNS_V2 SET "COMMENT" = ? WHERE CD_ID=? AND "COMMENT"
> = ? AND "COLUMN_NAME" = ? AND TYPE_NAME = ?,
> Error Msg = ORA-22848: cannot use CLOB type as comparison key{code}
> *Analysis:*
> When we ran a SELECT query like SELECT * FROM test_table, we noticed (via
> Oracle audit logs) that 18 unexpected UPDATE statements were issued on the
> COLUMNS_V2 table.
> These UPDATEs were not user-initiated, but instead triggered internally
> from DataNucleus, specifically during column descriptor retrieval (e.g.,
> loading embedded elements from MColumnDescriptor).
> One INSERT (expected) was for the actual CREATE TABLE DDL.
> However, these 18 UPDATEs are redundant, as no actual column change was
> made — these are simply side effects of dirty state synchronization inside
> the JDO lifecycle.
> The use of CLOB columns (TYPE_NAME) in Oracle becomes problematic in such
> UPDATE WHERE clauses due to the following error:
> {code:java}
> ORA-22848: cannot use CLOB type as comparison key{code}
>
> *Why This Is Not Oracle-Specific*
> We see the same issue in Derby (in terms of unnecessary updates),
> although without the CLOB-specific exception.
> In PostgreSQL or MySQL, the issue is not encountered because the Hive
> schemas use VARCHAR (STRING) instead of CLOB for these fields — and those
> types do support equality comparisons.
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