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https://issues.apache.org/jira/browse/CALCITE-7847?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated CALCITE-7847:
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Labels: pull-request-available (was: )
> Implicit coercion casts MULTISET operands of a comparison to ARRAY, and loses
> the nullability of ROW operands
> -------------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-7847
> URL: https://issues.apache.org/jira/browse/CALCITE-7847
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.42.0
> Reporter: Vladimir Sitnikov
> Priority: Major
> Labels: pull-request-available
>
> Comparing two MULTISET values whose element types differ casts both operands
> to ARRAY. On main (commit 843f468405, 1.43.0-SNAPSHOT), SqlToRelConverter
> translates
> {code:sql}
> select multiset[deptno] = multiset[cast(deptno as decimal(5, 2))] from dept
> {code}
> into
> {noformat}
> LogicalProject(EXPR$0=[=(CAST($SLICE($2)):DECIMAL(12, 2) NOT NULL ARRAY NOT
> NULL, CAST($SLICE($3)):DECIMAL(12, 2) NOT NULL ARRAY NOT NULL)])
> {noformat}
> Expected: both operands are cast to {{DECIMAL(12, 2) NOT NULL MULTISET NOT
> NULL}}.
> {{AbstractTypeCoercion#commonTypeForBinaryComparison}}, which the coercion
> calls, shows the same defect for the types directly:
> ||type1||type2||returned||expected||
> |INTEGER NOT NULL MULTISET NOT NULL|CHAR(1) NOT NULL MULTISET NOT
> NULL|INTEGER NOT NULL ARRAY NOT NULL|INTEGER NOT NULL MULTISET NOT NULL|
> |RecordType(INTEGER a) (nullable)|RecordType(CHAR(1) NOT NULL a) NOT
> NULL|RecordType(INTEGER a) NOT NULL|RecordType(INTEGER a) (nullable)|
> The other branches of the method, ARRAY and MAP included, return a nullable
> type when either operand is nullable (CALCITE-6741); the ROW branch returns
> NOT NULL. I did not find a query where the ROW defect changes the plan:
> SqlToRelConverter expands a ROW comparison into comparisons of its fields, so
> it shows only to callers of the method, such as a custom TypeCoercion.
> Cause: the ARRAY and MULTISET branch of {{commonTypeForBinaryComparison}}
> recurses into the element type for both, then always builds the result with
> {{createArrayType}}; the ROW branch returns
> {{createStructType(resultFields)}} without applying the nullability of the
> operands. The MULTISET branch came with CALCITE-6736, the ROW branch with
> CALCITE-6735.
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