ORCA: Validate hash function existence in IsOpHashJoinable

[yjhjstz]

postgres=#  set optimizer_enable_groupagg=off;
SET
postgres=# explain select * from atable group by a,k;
ERROR:  could not find hash function for hash operator 78765 (execGrouping.c:118) 

Fix execution-time error when operators have oprcanhash=true but lack actual hash functions. Previously, ORCA would generate HashAgg plans that failed at runtime with "could not find hash function for hash operator" errors.

This occurred when operators were marked with the 'hashes' option but only registered in btree operator families, not hash operator families. The fix adds validation using get_op_hash_functions() to ensure hash functions exist before allowing HashAgg plans, moving error detection from execution to planning time.

Fixes #ISSUE_Number

What does this PR do?

Type of Change

• Bug fix (non-breaking change)
• New feature (non-breaking change)
• Breaking change (fix or feature with breaking changes)
• Documentation update

Breaking Changes

Test Plan

• Unit tests added/updated
• Integration tests added/updated
• Passed make installcheck
• Passed make -C src/test installcheck-cbdb-parallel

Impact

Performance:

User-facing changes:

Dependencies:

Checklist

• Followed contribution guide
• Added/updated documentation
• Reviewed code for security implications
• Requested review from cloudberry committers

Additional Context

CI Skip Instructions

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[Copilot]

Pull request overview

This PR fixes a critical bug in ORCA where operators marked with oprcanhash=true but lacking actual hash support functions would cause runtime errors during query execution. The fix moves error detection from execution time to planning time by adding validation in IsOpHashJoinable().

Key Changes:

• Added hash function existence validation using get_op_hash_functions() in IsOpHashJoinable()
• Comprehensive regression test demonstrating the fix
• Test creates operators with the hashes flag but without valid hash operator families

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/backend/gpopt/gpdbwrappers.cpp	Enhanced IsOpHashJoinable() to validate hash function existence before allowing hash-based operations
src/test/regress/sql/gp_hashagg.sql	Added regression test creating custom type with operators marked hashable but lacking hash functions
src/test/regress/expected/gp_hashagg.out	Expected output showing queries succeed with the fix instead of failing at execution time

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