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https://issues.apache.org/jira/browse/HIVE-28622?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17925273#comment-17925273
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Denys Kuzmenko commented on HIVE-28622:
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Merged to master
Thanks [~harshalk] for the fix!
> Duplicate Entries in TXN_WRITE_NOTIFICATION_LOG Due to Oracle's Handling of
> Empty Strings
> -----------------------------------------------------------------------------------------
>
> Key: HIVE-28622
> URL: https://issues.apache.org/jira/browse/HIVE-28622
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2
> Reporter: Subhasis Gorai
> Assignee: Harshal Patel
> Priority: Major
> Labels: pull-request-available
>
> In Oracle, empty strings ({{{}''{}}}) are treated as {{NULL}} values for both
> {{VARCHAR2}} and {{CHAR}} data types. This behavior is unique to Oracle and
> can be confusing, as an empty string is typically considered distinct from
> {{NULL}} in other databases.
> As a result, the {{TXN_WRITE_NOTIFICATION_LOG}} table receives duplicate
> entries for a single Hive ACID transaction involving {{MERGE}} statements.
> This discrepancy leads to issues: the {{_files}} and {{_dumpmetadata}} files
> in a Hive ACID incremental dump will not align if the dump scope includes one
> or more {{MERGE}} statements. Consequently, the Hive ACID incremental
> {{LOAD}} fails at the target (DR), blocking subsequent replication executions.
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