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Posted to dev@calcite.apache.org by "Alessandro Solimando (Jira)" <ji...@apache.org> on 2020/10/24 18:08:00 UTC

[jira] [Created] (CALCITE-4354) ITEM operator does not support synthetic struct type

Alessandro Solimando created CALCITE-4354:
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             Summary: ITEM operator does not support synthetic struct type
                 Key: CALCITE-4354
                 URL: https://issues.apache.org/jira/browse/CALCITE-4354
             Project: Calcite
          Issue Type: Improvement
          Components: core
    Affects Versions: 1.27.0
            Reporter: Alessandro Solimando


The current implementation of the "ITEM" operator only supports struct/row type when this type if based on a class with named fields (that is, a non-synthetic type).  

For those non-synthetic struct types, the "ITEM" operator can be used to access named fields via a "string"-typed argument ([SqlItemOperator#96|https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/fun/SqlItemOperator.java#L96]).

The type checker accepts to apply "ITEM" on "ANY" type ([SqlItemOperator#49|https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/fun/SqlItemOperator.java#L49]), and the operand checker only accepts "string"-based values ([SqlItemOperator.java#105|https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/fun/SqlItemOperator.java#L105]).

[SqlValidatorTest.java#L11933|https://github.com/apache/calcite/blob/master/core/src/test/java/org/apache/calcite/test/SqlValidatorTest.java#L11933] is an example of application of the "ITEM" operator over a struct with named fields. 

However, the “getAllowedSignatures” method ([SqlItemOperator.java#116|https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/fun/SqlItemOperator.java#L116]) does not reflect this, and asserts a signature as follows: "<ARRAY>[<INTEGER>]" or "<MAP>[<VALUE>]".

"ITEM" operator could be enriched with the support of synthetic struct/row type, with a positional access to the fields with a signature "<ROW>[<INTEGER>]".



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