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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-4820) Optimize OrderBy for ClientAggregatePlan
Date Fri, 04 Jan 2019 02:25:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4820?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16733741#comment-16733741
] 

ASF GitHub Bot commented on PHOENIX-4820:
-----------------------------------------

Github user twdsilva commented on a diff in the pull request:

    https://github.com/apache/phoenix/pull/424#discussion_r245187754
  
    --- Diff: phoenix-core/src/main/java/org/apache/phoenix/expression/BaseExpression.java
---
    @@ -255,4 +255,15 @@ public boolean requiresFinalEvaluation() {
             return false;
         }
     
    +    @Override
    +    public boolean isCloneExpression()  {
    +       return isCloneExpressionByDeterminism(this);
    +    }
    +
    +    protected static boolean isCloneExpressionByDeterminism(BaseExpression expression)
{
    --- End diff --
    
    If isCloneExpression()  is implemented as follows, do you still need isCloneExpressionByDeterminism()
?
    ```
        @Override
        public boolean isCloneExpression()  {
           if(getDeterminism() == Determinism.PER_INVOCATION) {
                return true;
            }
            return false;
        }
    ``` 


> Optimize OrderBy for ClientAggregatePlan
> ----------------------------------------
>
>                 Key: PHOENIX-4820
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4820
>             Project: Phoenix
>          Issue Type: Improvement
>    Affects Versions: 4.14.0
>            Reporter: chenglei
>            Assignee: chenglei
>            Priority: Major
>             Fix For: 4.15.0
>
>         Attachments: PHOENIX-4820-4.x-HBase-1.3.patch, PHOENIX-4820.diff, PHOENIX-4820_v4-4.x-HBase-1.3.patch
>
>
> Given a table
> {code}
>   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}
> for following sql :
> {code}
>      select a.ak3 
>      from (select substr(pk1,1,1) ak1,substr(pk2,1,1) ak2,substr(pk3,1,1) ak3,substr(v1,1,1)
av1,substr(v2,1,1) av2 from test order by pk2,pk3 limit 10) a  group by a.ak3,a.av1 order
by a.ak3,a.av1
> {code}
> Intuitively, the above OrderBy statement {{order by a.ak3,a.av1}} should be compiled
out because it match the group by statement, but in fact it is not.
> The problem is caused by the {{QueryCompiler.compileSingleQuery}} and {{QueryCompiler.compileSingleFlatQuery}},for
 {{QueryCompiler.compileSingleQuery}} method,because the inner query has order by, so in line
520, local variable {{isInRowKeyOrder}} is false:
> {code}
> 519        context.setCurrentTable(tableRef);
> 520        boolean isInRowKeyOrder = innerPlan.getGroupBy() == GroupBy.EMPTY_GROUP_BY
&& innerPlan.getOrderBy() == OrderBy.EMPTY_ORDER_BY;
> {code}
> In {{QueryCompiler.compileSingleFlatQuery}},when {{OrderByCompiler.compile}} method is
invoked, the last parameter {{isInRowKeyOrder}} is false:
> {code}
> 562        OrderBy orderBy = OrderByCompiler.compile(context, select, groupBy, limit,
offset, projector,
> 563                groupBy == GroupBy.EMPTY_GROUP_BY ? innerPlanTupleProjector : null,
isInRowKeyOrder);
> {code}
> So in following line 156 for  {{OrderByCompiler.compile}},even though the {{tracker.isOrderPreserving}}
is true, the OrderBy  statement could not be compiled out.
> {code}
> 156       if (isInRowKeyOrder && tracker.isOrderPreserving()) {
> {code}      
> In my opinion, with GroupBy, in following line 563 for {{QueryCompiler.compileSingleFlatQuery}}
method, when we call 
> {{OrderByCompiler.compile}} method, we no need to conside the {{isInRowKeyOrder}},  just
like the previous parameter  {{tupleProjector}} does.
> {code}
>  562        OrderBy orderBy = OrderByCompiler.compile(context, select, groupBy, limit,
offset, projector,
>  563                groupBy == GroupBy.EMPTY_GROUP_BY ? innerPlanTupleProjector : null,
isInRowKeyOrder);
> {code}



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