Informix Error -9657: Cannot determine the data type of a collection in the given expression.

Cause and resolution

Cannot determine the data type of a collection in the given expression.

The data type of a collection used in the provided expression cannot be determined until run time. Casting the collection to a specific data type usually solves this problem.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-9657 fires when the data type of a collection used in an expression can't be determined until run time — per the official guidance.

A collection expression whose type can only be resolved at run time, per the official guidance — the direct, only cause.

Solutions / Resolution

Cast the collection to a specific data type, per the official guidance — this usually resolves the problem.

Examples

An ambiguous collection expression

SELECT CARDINALITY(some_expr) FROM tab;   -- -9657 if some_expr's collection type is ambiguous

Corrected — casting explicitly

SELECT CARDINALITY(CAST(some_expr AS LIST(INT NOT NULL))) FROM tab;

Diagnostic Checks

Identify the ambiguous collection expression, and add an explicit CAST to a specific collection type.

Related Errors / Related Topics

-9654 — "The element types of the collection are not unique; explicit casting is required." A related collection-typing error, on element-type uniqueness rather than the collection's overall type being undeterminable.

The collection expression's type couldn't be determined until run time — cast it to a specific type.