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From Aihua Xu <...@cloudera.com>
Subject Re: Review Request 47353: HIVE-13616: Investigate renaming a table without invalidating the column stats
Date Mon, 16 May 2016 18:04:22 GMT


> On May 16, 2016, 5:46 p.m., Ashutosh Chauhan wrote:
> > metastore/src/java/org/apache/hadoop/hive/metastore/HiveAlterHandler.java, lines
698-699
> > <https://reviews.apache.org/r/47353/diff/1/?file=1382994#file1382994line698>
> >
> >     Ideally this should happen in a single transaction on backend db. If you are
not planning to address that in this patch, please leave a TODO in here.

Are you referring to all the operations in single trsanction so that it can rollback completely?

To my understanding, it will perform all the operations in single transaction (of course it
depends on RawStore implementation). ObjectStore implementation keeps track of a openTrasactionCalls,
it will open a real transaction when it starts with 0 and it will do a real commit when it
ends with 0. If a db operation is part of a transaction, it will not start a new transaction.


> On May 16, 2016, 5:46 p.m., Ashutosh Chauhan wrote:
> > metastore/src/java/org/apache/hadoop/hive/metastore/HiveAlterHandler.java, line
651
> > <https://reviews.apache.org/r/47353/diff/1/?file=1382994#file1382994line651>
> >
> >     Don't use normalizeIdentifier() since that does trim() which will be incorrect.
Use .toLowerCase()

I don't get it. Can you explain a little? How does trim() of  the db name and table name cause
an issue? Are we allowing leading/trailing spaces in the db and tables names?


- Aihua


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/47353/#review133391
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On May 13, 2016, 7:17 p.m., Aihua Xu wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/47353/
> -----------------------------------------------------------
> 
> (Updated May 13, 2016, 7:17 p.m.)
> 
> 
> Review request for hive and Chaoyu Tang.
> 
> 
> Repository: hive-git
> 
> 
> Description
> -------
> 
> HIVE-13616: Investigate renaming a table without invalidating the column stats
> 
> 
> Diffs
> -----
> 
>   metastore/src/java/org/apache/hadoop/hive/metastore/HiveAlterHandler.java 0652b9db1a4224262611ff9258e871647442cfeb

>   ql/src/test/queries/clientpositive/rename_table_update_column_stats.q PRE-CREATION

>   ql/src/test/results/clientpositive/rename_table_update_column_stats.q.out PRE-CREATION

> 
> Diff: https://reviews.apache.org/r/47353/diff/
> 
> 
> Testing
> -------
> 
> Tests have been run and the failed tests don't seem to be related. 
> 
> To carry over the column stats during renaming the table, the patch 
> 1. Save affected column stats
> 2. Rename the table
> 3. Write the saved column stats for the new table.
> 
> In this order, column stats will find the foreign key when writing in 3).
> 
> 
> Thanks,
> 
> Aihua Xu
> 
>


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