Informix Error -640: QPlan sanity failure line-number.

Reasons / Common Causes

-640 is flagged by the official text as an internal error in the query plan (QPlan) the optimizer built for a statement — unusually among the sparse internal-error family, the official guidance offers a specific, concrete first thing to try: running UPDATE STATISTICS might fix it.

1. Stale or missing statistics causing the optimizer to build a query plan that fails an internal sanity check — the plausible mechanism behind the official guidance's UPDATE STATISTICS suggestion.
2. A genuine internal optimizer condition, per the official guidance's framing, with no other documented application-level cause if UPDATE STATISTICS doesn't resolve it.

Solutions / Resolution

1. Run UPDATE STATISTICS, per the official guidance, as the first and most concrete thing to try:

   UPDATE STATISTICS FOR TABLE orders;
   

   or, more broadly, across the tables involved in the failing statement.
2. If this recurs after running UPDATE STATISTICS, note all circumstances and contact IBM Informix Technical Support, per the official guidance.
3. Capture the specific line-number reported in the error message alongside the failing statement, for escalation if UPDATE STATISTICS doesn't resolve it.

Examples

Running UPDATE STATISTICS first

UPDATE STATISTICS FOR TABLE orders;
-- retry the statement that produced -640

Diagnostic Checks

1. Check how long it's been since UPDATE STATISTICS last ran on the tables involved in the failing statement, before escalating.
2. Capture the line-number from the error message and the exact failing statement for escalation if statistics don't resolve it.

Related Errors / Related Topics

No closely related error codes are cross-referenced for -640 in this set yet.

Unlike most internal errors in this range, the official guidance names a specific first fix to try — run UPDATE STATISTICS before escalating.