Jesus Camacho Rodriguez edited comment on HIVE-20090 at 7/11/18 5:37 PM:

Clean run, I have created a RB link : https://reviews.apache.org/r/67887/ . Can 
anyone review? Thanks

Cc [~gopalv] [~ashutoshc] [~djaiswal]

was (Author: jcamachorodriguez):
Clean run, I have created a RB link : https://reviews.apache.org/r/67887/ . Can 
someone review? Thanks

Cc [~gopalv] [~ashutoshc] [~djaiswal]

> Extend creation of semijoin reduction filters to be able to discover new 
> opportunities
> --------------------------------------------------------------------------------------
>                 Key: HIVE-20090
>                 URL: https://issues.apache.org/jira/browse/HIVE-20090
>             Project: Hive
>          Issue Type: Improvement
>          Components: Physical Optimizer
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>            Priority: Major
>         Attachments: HIVE-20090.01.patch, HIVE-20090.02.patch, 
> HIVE-20090.04.patch, HIVE-20090.05.patch
> Assume the following plan:
> {noformat}
> TS[0] - RS[1] - JOIN[4] - RS[5] - JOIN[8] - FS[9]
> TS[2] - RS[3] - JOIN[4] 
> TS[6] - RS[7] - JOIN[8]
> {noformat}
> Currently, {{TS\[6\]}} may only be reduced with the output of {{RS\[5\]}}, 
> i.e., input to join between both subplans.
> However, it may be useful to consider other possibilities too, e.g., reduced 
> by the output of {{RS\[1\]}} or {{RS\[3\]}}. For instance, this is important 
> when, given a large plan, an edge between {{RS[5]}} and {{TS[0]}} would 
> create a cycle, while an edge between {{RS[1]}} and {{TS[6]}} would not.
> This patch comprises two parts. First, it creates additional predicates when 
> possible. Secondly, it removes duplicate semijoin reduction 
> branches/predicates, e.g., if another semijoin that consumes the output of 
> the same expression already reduces a certain table scan operator (heuristic, 
> since this may not result in most efficient plan in all cases). Ultimately, 
> the decision on whether to use one or another should be cost-driven 
> (follow-up).

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