[jira] [Closed] (OPTIQ-349) Add heuristic join-optimizer that can generate bushy joins

["Julian Hyde (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OPTIQ-349?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Julian Hyde closed OPTIQ-349.
-----------------------------


Close issues resolved in release 0.9.0-incubating (2014-08-25).

> Add heuristic join-optimizer that can generate bushy joins
> ----------------------------------------------------------
>
>                 Key: OPTIQ-349
>                 URL: https://issues.apache.org/jira/browse/OPTIQ-349
>             Project: Optiq
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Julian Hyde
>             Fix For: 0.9.0-incubating
>
>
> Add OptimizeBushyJoinRule, a heuristic join-optimizer that can generate bushy joins.
> We already have LoptOptimizeJoinRule, which is capable of optimizing join order using heuristics, but it is not capable of generating bushy joins. We also have rules that can exhaustively generate all join-orderings (and OPTIQ-346 adds another rule) but this is impractical for N above about 7.
> This is a different approach to OPTIQ-299. Like 299, after choosing a global order, we want to be able to apply regular Optiq rules to optimize further; but  rather than adding "firewall" relational expressions to partitioning the graph, as advocated by 299, we might change the Volcano engine to allow regular rules if they immediately generate a cheaper relational expression or if they generate a cheaper relational expression after a maximum of N steps or C worsening of cost.



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