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From "Aljoscha Krettek (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (FLINK-7403) Remove expandLocalRef() before code generation
Date Fri, 22 Mar 2019 09:53:00 GMT

     [ https://issues.apache.org/jira/browse/FLINK-7403?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Aljoscha Krettek updated FLINK-7403:
------------------------------------
    Component/s:     (was: Table SQL / API)
                 Table SQL / Legacy Planner

> Remove expandLocalRef() before code generation
> ----------------------------------------------
>
>                 Key: FLINK-7403
>                 URL: https://issues.apache.org/jira/browse/FLINK-7403
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Legacy Planner
>            Reporter: Timo Walther
>            Assignee: Hequn Cheng
>            Priority: Major
>
> Currently, we expand local references before code generation. This means that expressions
that actually only need to be evaluated once, might be evaluated multiple times. We should
remove the expand step where possible.
> Take the following query as an example:
> {code:java}
> t.select(func0('c), func0('c), func0('c))
> {code}
> func0('c) is called three times for every input row even func0 is deterministic. It would
be nice if we can reuse it. 



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