[CALCITE-4652] AggregateExpandDistinctAggregatesRule must cast top aggregates to original type

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.27.0
• Fix Version/s: 1.28.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Taras Ledkov
• Reporter: Taras Ledkov
• Created: 15/Jun/21 11:49
• Updated: 20/Oct/21 05:24
• Resolved: 12/Aug/21 20:48

Description

The query SELECT COUNT(comm), COUNT(DISTINCT comm) FROM emp produces the plan below:

LogicalAggregate(group=[{}], EXPR$0=[$SUM0($1)], EXPR$1=[COUNT($0)])
  LogicalAggregate(group=[{0}], EXPR$0=[COUNT()])
    LogicalProject(COMM=[$6])
      LogicalTableScan(table=[[CATALOG, SALES, EMP]]) 

In case SUM type is expanded by override RelDataTypeSystem#deriveSumType the AggregateExpandDistinctAggregatesRule fails with assertion below:

Error:
java.lang.AssertionError: type mismatch:
aggCall type:
BIGINT NOT NULL
inferred type:
DECIMAL(19, 0) NOT NULL
    at org.apache.calcite.util.Litmus$1.fail(Litmus.java:32)
    at org.apache.calcite.plan.RelOptUtil.eq(RelOptUtil.java:2211)
    at org.apache.calcite.rel.core.Aggregate.typeMatchesInferred(Aggregate.java:443)
    at org.apache.calcite.rel.core.Aggregate.<init>(Aggregate.java:170)
    at org.apache.calcite.rel.logical.LogicalAggregate.<init>(LogicalAggregate.java:72)
    at org.apache.calcite.rel.logical.LogicalAggregate.copy(LogicalAggregate.java:154)
    at org.apache.calcite.rel.logical.LogicalAggregate.copy(LogicalAggregate.java:48)
    at org.apache.calcite.rel.rules.AggregateExpandDistinctAggregatesRule.convertSingletonDistinct(AggregateExpandDistinctAggregatesRule.java:401)
    ... 

Root cause:
the type of SUM aggregate doesn't match original type of the COUNT.

Issue Links

• is related to: CALCITE-4818 AggregateExpandDistinctAggregatesRule must infer correct data type for top aggregate calls
• links to: GitHub Pull Request #2439