Informix Error -639

Reasons / Common Causes

-639 fires when CREATE OPTICAL CLUSTER's FOR clause names TEXT/BYTE columns that don't all belong to the same optical family — per the official guidance, every column in the clause must share a single optical family.

1. The FOR clause naming columns spread across more than one optical family, per the official guidance — the direct, only cause.
2. A cluster definition assembled without checking each column's optical family assignment, assuming any set of TEXT/BYTE columns stored on optical media could be clustered together regardless of family.

Solutions / Resolution

1. Check that the columns specified for the optical cluster all belong to the same family, per the official guidance, before retrying.
2. Split the cluster definition by family if columns genuinely need to be clustered but span multiple families — create one optical cluster per family instead of one combined cluster.
3. Confirm each column's optical family assignment with whoever administers the Optical Subsystem configuration, if it isn't already documented which family each storage space belongs to.

Examples

The disallowed attempt

-- content_a is in optical family 'family1', content_b is in optical family 'family2'
CREATE OPTICAL CLUSTER mixed_cluster FOR content_a, content_b ...;
-- -639: content_a and content_b belong to different optical families

Corrected — one cluster per family

CREATE OPTICAL CLUSTER family1_cluster FOR content_a ...;
CREATE OPTICAL CLUSTER family2_cluster FOR content_b ...;

Diagnostic Checks

1. Confirm each column named in the FOR clause's optical family assignment before attempting the CREATE OPTICAL CLUSTER statement.

Related Errors / Related Topics

• -631 — "Cannot create optical cluster on column that is not TEXT or BYTE." A related optical-cluster restriction, on column type rather than family membership.
• -638 — "Cannot cluster TEXT or BYTE columns on non-optical media." A related restriction, on whether the column is on optical media at all rather than which family it belongs to.

Every column in the FOR clause must share a single optical family — split into one cluster per family if the columns genuinely span more than one.