[GitHub] [calcite] cshuo opened a new pull request #1835: [CALCITE-3830] The ‘approximate’ field should be considered when computing the digest of AggregateCall

[GitBox]

cshuo opened a new pull request #1835: [CALCITE-3830] The ‘approximate’ field 
should be considered when computing the digest of AggregateCall
URL: https://github.com/apache/calcite/pull/1835
 
 
   In planner optimization, the digest  of Aggregate node contains digest of 
its AggregateCall, i.e. Aggregate.toString, but currently 'approximate' filed 
of AggregateCall is not considered in toString() method, which may lead to the 
situation two different relNodes are considered as identical in planner 
optimizing phase. 
   
   Here is an example:
   ```sql
   select * from (
     select a, count(distinct b) from T group by a
     union all
     select a, approx_count_distinct(b) from T group by a
   )
   ```
   After applying a rule, the plan is:
   ```sql
   LogicalSink(name=[_DataStreamTable_1], fields=[a, EXPR$1], __id__=[96])
   +- LogicalProject(a=[$0], EXPR$1=[$1], __id__=[94])
      +- LogicalUnion(all=[true], __id__=[92])
         :- LogicalAggregate(group=[{0}], EXPR$1=[COUNT(DISTINCT $1)], 
__id__=[89])
         :  +- LogicalTableScan(table=[[default, _DataStreamTable_2]], 
__id__=[100])
         +- LogicalAggregate(group=[{0}], EXPR$1=[COUNT(DISTINCT $1)], 
__id__=[89])
            +- LogicalTableScan(table=[[default, _DataStreamTable_2]], 
__id__=[100])
   ```
   As showing in the example, after optimizing, these two Aggregates are 
considered as identical (both with 89 as relNode ID).

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