[CALCITE-2288] Type assertion error when reducing partially constant expression

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Fix Version/s: 1.19.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Laurent Goujon
• Created: 28/Apr/18 00:08
• Updated: 27/Feb/19 23:32
• Resolved: 27/Feb/19 23:32

Description

Probably a follow up of CALCITE-2041

The following query failed at planning time with an assertion error:

SELECT
  EXTRACT(SECOND FROM CAST(CASE WHEN TRUE THEN {ts '2018-01-01 01:23:45'} ELSE NULL END AS TIMESTAMP)) =
  EXTRACT(SECOND FROM d)
FROM (VALUES({ts '2018-01-01 01:23:45'})) tbl(d

Stacktrace is:

java.lang.AssertionError: Cannot add expression of different type to set:
set type is RecordType(BOOLEAN EXPR$0) NOT NULL
expression type is RecordType(BOOLEAN NOT NULL EXPR$0) NOT NULL
set is rel#4:LogicalProject(input=HepRelVertex#3,EXPR$0==(EXTRACT(FLAG(SECOND), CAST(CASE(true, 2018-01-01 01:23:45, null)):TIMESTAMP(0)), EXTRACT(FLAG(SECOND), $0)))
expression is LogicalProject#6
	at org.apache.calcite.plan.RelOptUtil.verifyTypeEquivalence(RelOptUtil.java:413)
	at org.apache.calcite.plan.hep.HepRuleCall.transformTo(HepRuleCall.java:57)
	at org.apache.calcite.plan.RelOptRuleCall.transformTo(RelOptRuleCall.java:234)
	at org.apache.calcite.rel.rules.ReduceExpressionsRule$ProjectReduceExpressionsRule.onMatch(ReduceExpressionsRule.java:290)
	at org.apache.calcite.plan.AbstractRelOptPlanner.fireRule(AbstractRelOptPlanner.java:317)
	at org.apache.calcite.plan.hep.HepPlanner.applyRule(HepPlanner.java:556)
	at org.apache.calcite.plan.hep.HepPlanner.applyRules(HepPlanner.java:415)
	at org.apache.calcite.plan.hep.HepPlanner.executeInstruction(HepPlanner.java:252)
	at org.apache.calcite.plan.hep.HepInstruction$RuleInstance.execute(HepInstruction.java:127)
	at org.apache.calcite.plan.hep.HepPlanner.executeProgram(HepPlanner.java:211)
	at org.apache.calcite.plan.hep.HepPlanner.findBestExp(HepPlanner.java:198)
...

As far as I can tell, the issue is in ReduceExpressionRules#reduceExpressions: when the expression is partially reduced, the reduced expression lost its type nullability, which is not added back by the simplifier.

Issue Links

• links to: GitHub Pull Request #709
• links to: PR#709