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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-5524) Support early out for code generated conjunctive conditions
Date Tue, 21 Feb 2017 06:51:44 GMT

    [ https://issues.apache.org/jira/browse/FLINK-5524?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15875459#comment-15875459
] 

ASF GitHub Bot commented on FLINK-5524:
---------------------------------------

GitHub user KurtYoung opened a pull request:

    https://github.com/apache/flink/pull/3372

    [FLINK-5524] [table] Support early out for code generated AND/OR condition

    For condition like a AND b, if the result of a is false, we can save b from execution.
    
    For condition like a OR b, if the result of a is true, we can also save b from execution.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/KurtYoung/flink flink-5524

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/flink/pull/3372.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #3372
    
----
commit 4f8c07ffc6ac99da67803114edb732e20df793e6
Author: Kurt Young <ykt836@gmail.com>
Date:   2017-02-21T06:35:17Z

    [FLINK-5524] [table] Support early out for code generated AND/OR conditions

----


> Support early out for code generated conjunctive conditions
> -----------------------------------------------------------
>
>                 Key: FLINK-5524
>                 URL: https://issues.apache.org/jira/browse/FLINK-5524
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>    Affects Versions: 1.2.0, 1.1.4, 1.3.0
>            Reporter: Fabian Hueske
>            Assignee: Kurt Young
>
> Currently, all nested conditions for a conjunctive predicate are evaluated before the
conjunction is checked.
> A condition like {{(v1 == v2) && (v3 < 5)}} would be compiled into
> {code}
> boolean res1;
> if (v1 == v2) {
>   res1 = true;
> } else {
>   res1 = false;
> }
> boolean res2;
> if (v3 < 5) {
>   res2 = true;
> } else {
>   res2 = false;
> }
> boolean res3;
> if (res1 && res2) {
>   res3 = true;
> } else {
>   res3 = false;
> }
> if (res3) {
>   // emit something
> }
> {code}
> It would be better to leave the generated code as early as possible, e.g., with a {{return}}
instead of {{res1 = false}}. The code generator needs a bit of context information for that.



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