Informix Error -679: Cannot read constraint violation data for constraint constraint-name.

Reasons / Common Causes

-679 is flagged by the official text as an internal error: the server can't read the diagnostic data it maintains about which row(s) violate a given constraint — per the official guidance, the accompanying ISAM error carries the specific reason.

1. An underlying ISAM-level error while reading the constraint-violation data, per the official guidance's pointer to checking the accompanying ISAM error — the only documented path to the specific cause.
2. Storage-level issues (space, corruption) in the area holding this diagnostic data, a plausible category given similar internal errors elsewhere in this range, though not explicitly named by the sparse official text.

Solutions / Resolution

1. Check the accompanying ISAM error code, per the official guidance — the only documented path to the specific underlying cause.
2. If this recurs, note all circumstances and contact IBM Informix Technical Support, per the official guidance.
3. Capture the specific constraint-name reported, along with the accompanying ISAM error, for escalation.

Examples

Capturing circumstances for escalation

-- Record the constraint-name and the accompanying ISAM error code
-- reported alongside -679 for escalation.

Diagnostic Checks

1. Check the accompanying ISAM error code first, per the official guidance.
2. Capture the specific constraint name for escalation if the ISAM error doesn't clarify the cause.

Related Errors / Related Topics

• -680 — "Cannot write constraint violation data for constraint constraint-name." The write-side counterpart to this read-side failure.
• -682 — "Error reading constraint index on table table-name." A related internal constraint-validation error, about the index itself rather than violation diagnostic data.

An internal failure reading constraint-violation diagnostic data — check the accompanying ISAM error for the specific cause.