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Krisztian Kasa commented on HIVE-23206:
---------------------------------------
[~vgarg]
I fixed the checkstyle issue what I was able to in [^HIVE-23206.5.patch]
1. added javadoc to *HiveJoinProjectTransposeRule*
2. *HiveJoinProjectTransposeRuleBase* can't be a final class because *HiveJoinProjectBtwJoinTransposeRule*
extends it. (This could be a bug in the checkstyle rule?)
3. Left intact the TODO.
Also left comments on RB about why shared optimizer is unable to merge joins.
> Project not defined correctly after reordering a join
> -----------------------------------------------------
>
> Key: HIVE-23206
> URL: https://issues.apache.org/jira/browse/HIVE-23206
> Project: Hive
> Issue Type: Bug
> Components: CBO
> Reporter: Steve Carlin
> Assignee: Krisztian Kasa
> Priority: Major
> Attachments: HIVE-23206.1.patch, HIVE-23206.2.patch, HIVE-23206.3.patch, HIVE-23206.4.patch,
HIVE-23206.5.patch
>
>
> The following highlighted line seems to be incorrect in the test suite:
> [https://github.com/apache/hive/blob/master/ql/src/test/results/clientpositive/perf/tez/cbo_query95.q.out#L89]
> Note that the project takes all the columns from the table scan, yet it only needs a
couple of them.
> I did some very small debugging on this. When I removed the applyJoinOrderingTransform
here: [https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/parse/CalcitePlanner.java#L1897]
> ... the problem goes away. So presumably one of the rules in there is causing the problem.
> Here is a slightly simplified version of the query which has the same problem (using
the same tpc-ds database):
> explain cbo with ws_wh as
> (select ws1.ws_order_number
> from web_sales ws1,web_returns wr2
> where ws1.ws_order_number = wr2.wr_order_number)
> select
> ws_order_number
> from
> web_sales ws1
> where
> ws1.ws_order_number in (select wr_order_number
> from web_returns,ws_wh
> where wr_order_number = ws_wh.ws_order_number)
>
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