[jira] [Commented] (PHOENIX-7352) Improve OrderPreservingTracker to support extracting partial ordering columns for TupleProjectionPlan

["chenglei (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PHOENIX-7352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17867979#comment-17867979 ] 

chenglei commented on PHOENIX-7352:
-----------------------------------

Pushed to 5.2+, thanks [~tkhurana] for review!

> Improve OrderPreservingTracker to support extracting partial ordering columns for TupleProjectionPlan 
> ------------------------------------------------------------------------------------------------------
>
>                 Key: PHOENIX-7352
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-7352
>             Project: Phoenix
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 5.2.0
>            Reporter: chenglei
>            Assignee: chenglei
>            Priority: Major
>             Fix For: 5.2.1, 5.3.0
>
>
> This is an improvement for  PHOENIX-5148: 
> Given a table:
> {code:java}
>   create table test ( 
>        pk1 varchar not null , 
>        pk2 varchar not null, 
>        pk3 varchar not null,
>        v1 varchar, 
>        v2 varchar, 
>        CONSTRAINT TEST_PK PRIMARY KEY ( 
>              pk1,
>              pk2,
>              pk3 ))
> {code}
> PHOENIX-5148 optimized following sql to compile outer {{OrderBy}}  "order by v2, pk3" because it matches the inner query {{OrderBy}} "order by t.v2, t.pk3, t.v1":
> {code:java}
> select v1 from (select v1, v2, pk3 from test t where pk1 = '6' order by t.v2, t.pk3, t.v1 limit 10) a order by v2, pk3
> {code}
> But if we make a small change to the sql above, just remove the {{t.v1}} in  inner query {{OrderBy}} "order by t.v2, t.pk3, t.v1":
> {code:java}
> select v1 from (select v1, v2, pk3 from test t where pk1 = '6' order by t.v2, t.pk3 limit 10) a order by v2, pk3
> {code}
> Obviously, the outer {{OrderBy}} "order by v2,pk3" should still be compiled out because it matches the inner query OrderBy "order by t.v2, t.pk3" , but unfortunately it could not be compiled out now.
> That is because for the inner query of the second sql, we infer the output {{OrderBy}} from "select v1, v2, pk3" based on "order by t.v2, t.pk3". This work is done by {{OrderPreservingTracker}} in {{TupleProjectionPlan}} . But for {{OrderPreservingTracker}}, it could not support extracting partial ordering columns, when it finds that {{v1}} in "select v1, v2, pk3" does not appear in "order by t.v2, t.pk3",   {{OrderPreservingTracker.isOrderPreserving}} returns false, and 
> {{OrderPreservingTracker.getOrderPreservingTrackInfos}} returns an empty list in {{TupleProjectionPlan}}. 
> We should modify {{OrderPreservingTracker}} to make {{OrderPreservingTracker.getOrderPreservingTrackInfos}} could also extract partial continuous ordering columns which start from the first column even if {{OrderPreservingTracker.isOrderPreserving}} is false.  That is to say, even if {{v1}} in "select v1, v2, pk3" does not appear in "order by t.v2, t.pk3", it will return the partial ordered "v2, pk3".



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