[CALCITE-7614] UNNEST of an unqualified struct-rooted array path fails validation: "Column 's.s' not found"

[takaaki7]

Jira Link

CALCITE-7614

Changes Proposed

When the operand of UNNEST is an unqualified identifier whose leading component is a PEEK_FIELDS struct column, validation fails:

-- table T has column S: STRUCT<arr ARRAY<VARCHAR>> with StructKind.PEEK_FIELDS

SELECT * FROM t AS r CROSS JOIN UNNEST(r.s.arr) AS x;  -- OK (table-qualified)
SELECT * FROM t        CROSS JOIN UNNEST(s.arr)   AS x;  -- FAILS: "Column 'S.S' not found in table 'T'"

Root cause

DelegatingScope.fullyQualify qualifies the unqualified operand by first resolving the table that owns the PEEK_FIELDS column. That resolution re-enters validation of the UNNEST namespace, which expands the same operand SqlIdentifier and rewrites its name list in place to the fully-qualified form (SqlValidatorImpl.validateIdentifier → SqlIdentifier.assignNamesFrom). Control then returns to fullyQualify, which re-qualifies the now-already-qualified identifier, prepending the table/struct segment a second time and producing the doubled S.S.

The table-qualified form is unaffected because re-qualifying r.s.arr is idempotent.

Fix

DelegatingScope.fullyQualify now snapshots the identifier before the re-entrant resolution and builds the qualified PEEK_FIELDS identifier from that snapshot, so it always works from the original names. The change is a no-op when no re-entrant rewrite occurs. The production change is confined to DelegatingScope.java.

Tests

• New SqlValidatorTest.testUnnestPeekFieldsArrayColumn covering qualified/unqualified × CROSS JOIN/comma-join.
• Added a PEEK_FIELDS struct type containing an array field (Fixture.peekArrayType) and a DEPT_NESTED_PEEK(DEPTNO, S) table in the mock catalog (MockCatalogReaderSimple), since no such column existed.
• Updated SqlAdvisorTest's expected SALES completion list to include the new table.

./gradlew :core:test passes (15649 tests, 0 failed).

[takaaki7]

@julianhyde could you review this small DelegatingScope.fullyQualify fix when you have a moment? Thanks!

[mihaibudiu]

I would call this "originalIdentifier"

[takaaki7]

Done

[mihaibudiu]

CI is not happy, can you take a look?

[takaaki7]

Fixed.

[mihaibudiu]

Please squash the commits so we can merge this.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[takaaki7]

Squashed

[xiedeyantu]

@takaaki7 Please note that Calcite does not recommend using agents like Claude as collaborators; please only include your own contributions in subsequent submissions.

[mihaibudiu]

I don't think we have a policy not to use agents. A tool that solves the problem is a good tool. But the users should scrutinize code from the agents carefully before submitting a PR, ensuring that it is compact and clear. Sometimes these agents solve simple problems in very complicated ways. You cannot expect other reviewers to clean up after agents, you have to do it yourself before you submit.

[takaaki7]

Thanks for the feedbacks. Understood on the co-author tags. I'll properly review things on my end to avoid AI slop.