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https://issues.apache.org/jira/browse/CALCITE-4302?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Danny Chen resolved CALCITE-4302.
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Fix Version/s: 1.27.0
Assignee: Danny Chen
Resolution: Fixed
Fixed in
[c7fdae2|https://github.com/apache/calcite/commit/c7fdae22fb0e6b220152f05a7343ce5569283a83],
thanks for your PR, [~botong] ~
> Improve cost propagation in volcano to avoid re-propagation
> -----------------------------------------------------------
>
> Key: CALCITE-4302
> URL: https://issues.apache.org/jira/browse/CALCITE-4302
> Project: Calcite
> Issue Type: Improvement
> Reporter: Botong Huang
> Assignee: Danny Chen
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.27.0
>
> Time Spent: 5h 40m
> Remaining Estimate: 0h
>
> CALCITE-3330 changed the cost propagation in volcano from DFS to BFS.
> However, there is still room for improvement. A subset can be updated more
> than once in a cost propagation process. For instance, A -> D, A -> B -> C ->
> D. When subset A has an update, using BFS subset D (and thus all subsets
> above/after D) can be updated twice, first via A -> D and then C -> D. We can
> further improve the BFS by always popping the relNode with the smallest cost
> from the queue, similar to the Dijkstra algorithm. So that whenever a relNode
> is popped from the queue, its current best cannot be further deceased any
> more. As a result, all subsets will only be propagated at most once.
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