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https://issues.apache.org/jira/browse/HIVE-17657?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16459339#comment-16459339
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Sergey Shelukhin commented on HIVE-17657:
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Addressed the CR feedback.
> export/import for MM tables is broken
> -------------------------------------
>
> Key: HIVE-17657
> URL: https://issues.apache.org/jira/browse/HIVE-17657
> Project: Hive
> Issue Type: Sub-task
> Components: Transactions
> Reporter: Eugene Koifman
> Assignee: Sergey Shelukhin
> Priority: Major
> Labels: mm-gap-2
> Attachments: HIVE-17657.01.patch, HIVE-17657.02.patch,
> HIVE-17657.03.patch, HIVE-17657.04.patch, HIVE-17657.05.patch,
> HIVE-17657.06.patch, HIVE-17657.patch
>
>
> there is mm_exim.q but it's not clear from the tests what file structure it
> creates
> On import the txnids in the directory names would have to be remapped if
> importing to a different cluster. Perhaps export can be smart and export
> highest base_x and accretive deltas (minus aborted ones). Then import can
> ...? It would have to remap txn ids from the archive to new txn ids. This
> would then mean that import is made up of several transactions rather than 1
> atomic op. (all locks must belong to a transaction)
> One possibility is to open a new txn for each dir in the archive (where
> start/end txn of file name is the same) and commit all of them at once (need
> new TMgr API for that). This assumes using a shared lock (if any!) and thus
> allows other inserts (not related to import) to occur.
> What if you have delta_6_9, such as a result of concatenate? If we stipulate
> that this must mean that there is no delta_6_6 or any other "obsolete" delta
> in the archive we can map it to a new single txn delta_x_x.
> Add read_only mode for tables (useful in general, may be needed for upgrade
> etc) and use that to make the above atomic.
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