[PHOENIX-4820] Optimize OrderBy for ClientAggregatePlan - ASF JIRA

XML

Word

Printable

JSON

Details

Type: Improvement
Status: Closed
Priority: Major
Resolution: Fixed
Affects Version/s: 4.14.0
Fix Version/s: 4.15.0, 5.1.0
Component/s: None
Labels:
None

Description

Given a table

  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 ))

for following sql :

     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

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:

519        context.setCurrentTable(tableRef);
520        boolean isInRowKeyOrder = innerPlan.getGroupBy() == GroupBy.EMPTY_GROUP_BY && innerPlan.getOrderBy() == OrderBy.EMPTY_ORDER_BY;

In QueryCompiler.compileSingleFlatQuery,when OrderByCompiler.compile method is invoked, the last parameter isInRowKeyOrder is false:

562        OrderBy orderBy = OrderByCompiler.compile(context, select, groupBy, limit, offset, projector,
563                groupBy == GroupBy.EMPTY_GROUP_BY ? innerPlanTupleProjector : null, isInRowKeyOrder);

So in following line 156 for OrderByCompiler.compile,even though the tracker.isOrderPreserving is true, the OrderBy statement could not be compiled out.

156       if (isInRowKeyOrder && tracker.isOrderPreserving()) {

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.

 562        OrderBy orderBy = OrderByCompiler.compile(context, select, groupBy, limit, offset, projector,
 563                groupBy == GroupBy.EMPTY_GROUP_BY ? innerPlanTupleProjector : null, isInRowKeyOrder);