[CALCITE-7442] fix correlated variable's index inside subquery

[yashlimbad]

Jira Link

CALCITE-7442

Changes

Adjust offset of correlated variable inside subquery when pushing filter via FilterJoinRule.java

[xiedeyantu]

There is an error in the CI that needs to be resolved.

[yashlimbad]

Updated the Code.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
90.0% Coverage on New Code
9.3% Duplication on New Code

See analysis details on SonarQube Cloud

[Copilot]

Pull request overview

Fixes a decorrelation/planning correctness issue (CALCITE-7442) where a correlated variable’s field index inside a subquery can become incorrect after FilterJoinRule pushes filters.

Changes:

• Add a regression test that exercises FILTER_INTO_JOIN + FILTER_SUB_QUERY_TO_CORRELATE and then decorrelates, asserting expected plans.
• Extend FilterJoinRule to propagate correlation-variable sets when creating pushed-down filters (and when keeping an above-join filter).
• Enhance RelOptUtil.classifyFilters shifting logic so correlated field accesses inside RexSubQuery.rel can be adjusted during filter pushdown.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
core/src/test/java/org/apache/calcite/sql2rel/RelDecorrelatorTest.java	Adds a regression test covering correlated variable index behavior through filter pushdown + decorrelation.
core/src/main/java/org/apache/calcite/rel/rules/FilterJoinRule.java	Tracks correlation variables when constructing new Filters after pushdown.
core/src/main/java/org/apache/calcite/plan/RelOptUtil.java	Extends filter-shifting to also adjust correlated field accesses inside subqueries.

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[xiedeyantu]

I'm not sure if these comments will be helpful, as I'm not very familiar with this specific area. If someone more knowledgeable doesn't review this PR within the next few days, I'll give it a try myself.

[yashlimbad]

some comments were looking helpful so I updated code now will check by running build if it goes through and push accordingly! 😄 it's fine if someone reviews code in few days, but I feel @julianhyde would be the best to review this because I see only his commit on RelOptUtil which I updated which is called from FilterJoinRule

[yashlimbad]

sometimes the tests passes sometimes fails randomly with below error in CI

Execution failed for task ':arrow:test'.
> Could not resolve all dependencies for configuration ':arrow:jacocoAgent'.
   > Could not load module metadata from /home/jenkins/.gradle/caches/modules-2/metadata-2.106/descriptors/org.jacoco/org.jacoco.agent/0.8.11/26c913274550a0b2221f47a0fe2d2358/descriptor.bin

even tho gradlew build is passed
it will be good if this CI run is consistent