Informix Error -629

Reasons / Common Causes

-629 fires when the coordinator can't end an Informix STAR two-phase-commit transaction that was heuristically rolled back — a transaction where a participant made an independent (heuristic) decision to roll back rather than waiting for the coordinator's final instruction, and the coordinator now can't cleanly close it out. Per the official guidance, the transaction remains open, but Informix STAR's automatic recovery mechanics eventually end it; no administrative intervention is required.

1. A participant's heuristic rollback decision (made independently, typically due to a timeout or local administrative action) complicating the coordinator's normal end-transaction bookkeeping.
2. A local failure on the coordinator server while processing the heuristically-rolled-back transaction's end step, per the official guidance's pointer to checking the accompanying ISAM error.
3. Network/communication issues between coordinator and participant around the time of the heuristic decision, contributing to the coordinator's difficulty ending the transaction cleanly.

Solutions / Resolution

1. No administrative intervention is required, per the official guidance — Informix STAR's automatic recovery mechanics eventually end the transaction.
2. Check the accompanying ISAM error, per the official guidance, for the specific reason, if investigation is needed.
3. If heuristic rollbacks are happening frequently, investigate why participants are making independent rollback decisions (commonly a timeout setting too aggressive for the distributed transaction's actual duration) rather than only focusing on this specific end-transaction symptom.

Examples

Investigating frequent heuristic rollbacks

$ onstat -G

onstat -G lists global transactions generated through the TP/XA library (external XA transaction managers such as Tuxedo); it isn't documented as covering Informix STAR's own server-to-server 2PC state specifically, so treat it as relevant only if TP/XA is also involved. For STAR itself, watch the online log for heuristic-rollback entries. If heuristic rollbacks recur often, review the timeout configuration governing how long a participant waits before making an independent decision.

Diagnostic Checks

1. Check the accompanying ISAM error for the specific local reason.
2. Review participant timeout configuration if heuristic rollbacks (and this error) recur frequently, since that's the more actionable root cause to address.

Related Errors / Related Topics

• -627 — "Cannot prepare coordinator for two-phase commit." Same family, at the earlier prepare step.
• -628 — "Cannot end two-phase commit transaction at coordinator." Same family, for the ordinary (non-heuristic) end-transaction case.
• -630 — "Cannot prepare database server server-name for commit." Same family, naming a specific participant server.

Part of the Informix STAR two-phase-commit error family, specific to a heuristically rolled back transaction — if this recurs, look at why participants are making independent rollback decisions in the first place.