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https://issues.apache.org/jira/browse/HIVE-30227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18135257#comment-18135257
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Denys Kuzmenko commented on HIVE-30227:
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cc [~kkasa]
> Iceberg: a V3 materialized view rebuild in insert-delete mode writes two DVs
> per data file
> ------------------------------------------------------------------------------------------
>
> Key: HIVE-30227
> URL: https://issues.apache.org/jira/browse/HIVE-30227
> Project: Hive
> Issue Type: Bug
> Reporter: Denys Kuzmenko
> Priority: Major
>
> An incremental rebuild of a materialized view in insert-delete mode
> (AGGREGATE_INSERT_DELETE_REBUILD: a V3 Iceberg materialized view with
> count(*) over full-ACID sources) deletes through two DELETE branches: one for
> the groups it updates and one for the groups whose count drops to 0. Neither
> branch is distributed by FILE__PATH, and a data file can hold rows of both,
> so a data file can get several DVs in one commit, which Iceberg then merges
> at commit time (merged-dvs). HIVE-30112 made DELETE, UPDATE and MERGE write
> one DV per data file.
> *Fix*
> - Distribute the delete branches of the rebuild by
> HiveStorageHandler#acidDistributeColumns, as the DML rewriters do
> (AlterMaterializedViewRebuildAnalyzer, MaterializedViewASTBuilder,
> NonNativeAcidMaterializedViewASTBuilder); the first commit of the HIVE-30112
> PR (#6924) has this part with iceberg_mv_rebuild_dv_per_file.q.
> - Combine the two delete branches into one, as SplitMergeRewriter does for a
> MERGE with UPDATE and DELETE clauses.
> Found in the review of HIVE-30112.
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