[FLINK-14030] IS_NULL is optimized to incorrect results

• Type: Bug
• Status: Open
• Priority: Not a Priority
• Resolution: Unresolved
• Affects Version/s: 1.9.0
• Component/s: Table SQL / Planner
• Labels: auto-deprioritized-major auto-deprioritized-minor
• Assignee: Unassigned
• Reporter: Leonard Xu
• Created: 09/Sep/19 15:19
• Updated: 22/Nov/21 22:38

Description

testAllApis() unit tests will run fail because planner make a conversion
from [ifThenElse(isNull(plus(f0, f1)), 'null', 'not null')]
to [CASE(OR(IS NULL($0), IS NULL($1)), _UTF-16LE'null', _UTF-16LE'not null')]
which is not a equivalence conversion. The result of expression 'f0 + 'f1 should be null
when the result overflows even if its two operands both are not null.

It's easy to reproduce as following:
testAllApis(
'f0 + 'f1,
"f1 + f1",
"f1 + f1",
"null")// the result should be null because overflow

override def testData: Row =

{ val testData = new Row(2) testData.setField(0, BigDecimal("1e10").bigDecimal) testData.setField(1, BigDecimal("0").bigDecimal) testData }

override def typeInfo: RowTypeInfo =

{ new RowTypeInfo( /* 0 */ fromLogicalTypeToTypeInfo(DECIMAL(38, 10)), /* 1 */ fromLogicalTypeToTypeInfo(DECIMAL(38, 28)) ) }

 

Issue Links

• relates to: CALCITE-3368 PLUS, MINUS and TIMES should be unsafe when simplifying ‘expression IS NULL’