Fix Issue 2289: handle empty list in IN expression #2294
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NOTE: This PR was created with AI tools and a human. When evaluating 'x IN []' with an empty list, the transform_AEXPR_IN function would return NULL because no expressions were processed. This caused a 'cache lookup failed for type 0' error downstream. This fix adds an early check for the empty list case: - 'x IN []' returns false (nothing can be in an empty list) Additional NOTE: Cypher does not have 'NOT IN' syntax. To check if a value is NOT in a list, use 'NOT (x IN list)'. The NOT operator will invert the false from an empty list to true as expected. The fix returns a boolean constant directly, avoiding the NULL result that caused the type lookup failure. Added regression tests. modified: regress/expected/expr.out modified: regress/sql/expr.sql modified: src/backend/parser/cypher_expr.c
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Pull request overview
This PR fixes a "cache lookup failed for type 0" error that occurred when evaluating expressions like x IN [] with an empty list. The root cause was that the transform_AEXPR_IN function would return NULL when processing an empty list, leading to a type lookup failure downstream.
Key Changes:
- Added an early check for empty lists in transform_AEXPR_IN that returns a boolean constant (false for IN, true for the internal <> operator)
- Added comprehensive regression tests covering different data types with empty list IN expressions
- Added test for NOT (x IN []) to verify proper negation behavior
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| src/backend/parser/cypher_expr.c | Added early return for empty list case before processing elements, preventing NULL result that caused the type lookup error |
| regress/sql/expr.sql | Added test cases for x IN [] with various data types (integer, string, null, list) and NOT expressions |
| regress/expected/expr.out | Expected output showing all x IN [] cases return false and NOT (x IN []) cases return true |
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MuhammadTahaNaveed
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Jan 9, 2026
jrgemignani
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Jan 21, 2026
NOTE: This PR was created with AI tools and a human. When evaluating 'x IN []' with an empty list, the transform_AEXPR_IN function would return NULL because no expressions were processed. This caused a 'cache lookup failed for type 0' error downstream. This fix adds an early check for the empty list case: - 'x IN []' returns false (nothing can be in an empty list) Additional NOTE: Cypher does not have 'NOT IN' syntax. To check if a value is NOT in a list, use 'NOT (x IN list)'. The NOT operator will invert the false from an empty list to true as expected. The fix returns a boolean constant directly, avoiding the NULL result that caused the type lookup failure. Added regression tests. modified: regress/expected/expr.out modified: regress/sql/expr.sql modified: src/backend/parser/cypher_expr.c
MuhammadTahaNaveed
pushed a commit
that referenced
this pull request
Jan 21, 2026
NOTE: This PR was created with AI tools and a human. When evaluating 'x IN []' with an empty list, the transform_AEXPR_IN function would return NULL because no expressions were processed. This caused a 'cache lookup failed for type 0' error downstream. This fix adds an early check for the empty list case: - 'x IN []' returns false (nothing can be in an empty list) Additional NOTE: Cypher does not have 'NOT IN' syntax. To check if a value is NOT in a list, use 'NOT (x IN list)'. The NOT operator will invert the false from an empty list to true as expected. The fix returns a boolean constant directly, avoiding the NULL result that caused the type lookup failure. Added regression tests. modified: regress/expected/expr.out modified: regress/sql/expr.sql modified: src/backend/parser/cypher_expr.c
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NOTE: This PR was created with AI tools and a human.
When evaluating 'x IN []' with an empty list, the transform_AEXPR_IN function would return NULL because no expressions were processed. This caused a 'cache lookup failed for type 0' error downstream.
This fix adds an early check for the empty list case:
Additional NOTE: Cypher does not have 'NOT IN' syntax. To check if a value is NOT in a list, use 'NOT (x IN list)'. The NOT operator will invert the false from an empty list to true as expected.
The fix returns a boolean constant directly, avoiding the NULL result that caused the type lookup failure.
Added regression tests.
modified: regress/expected/expr.out
modified: regress/sql/expr.sql
modified: src/backend/parser/cypher_expr.c