Mark Grey created CALCITE-4972:
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Summary: Qualify subfields of array columns containing structs in
return of getFieldOrigins
Key: CALCITE-4972
URL: https://issues.apache.org/jira/browse/CALCITE-4972
Project: Calcite
Issue Type: Improvement
Components: core
Affects Versions: 1.28.0
Reporter: Mark Grey
Attempting to follow on the [suggestions from Julian in this
thread|https://lists.apache.org/thread/pdpqtzy5mtzlpdbhwghbty6cj0jgc86l], found
a potential improvement.
Given a table schema containing a repeated array of structs and a query
projecting fields of that struct via UNNEST, the present implementation of
{{getFieldOrigins}} in {{SqlValidatorImpl}} will return a list representation
suggesting that the subfield is actually a member of the top level table row
type.
For example, when using the [DEPT_NESTED table from the
MockCatalogReaderSimple|https://github.com/apache/calcite/blob/master/testkit/src/main/java/org/apache/calcite/test/catalog/MockCatalogReaderSimple.java#L152-L159]
within tests with the following query:
{code:sql}
select e.empno from dept_nested, unnest(employees) as e
{code}
The return value will be:
{code}
{CATALOG.SALES.DEPT_NESTED.EMPNO}
{code}
Rather than:
{code}
{CATALOG.SALES.DEPT_NESTED.EMPLOYEES.EMPNO}
{code}
No such column {{EMPNO}} exists in the root schema of the DEPT_NESTED table.
[The javadoc for the method
|https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/validate/SqlValidator.java#L717-L728]however
suggests that the return from this method should always be four entries long,
although it would seem this doesn't account for nesting. Is this intended
behavior, or should {{column}} entry of this list be of variable length?
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