Informix Error -868

-868 Cannot check constraints on the attaching table.

You cannot attach a table if a check, referential, primary-key, or not null constraint exists on the surviving table.

Drop any check, referential, primary-key, or not null constraint. Then attach the table and if you still want to use the constraint, re-create it.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-868 fires when ALTER FRAGMENT ... ATTACH is attempted while a check, referential, primary-key, or NOT NULL constraint exists on the surviving table — per the official guidance, these constraints must be dropped before the attach, then re-created afterward if still needed.

A check, referential, primary-key, or NOT NULL constraint present on the surviving table, per the official guidance — the direct, only cause; the attach operation can't validate these constraints against the newly-combined data mid-operation.

Solutions / Resolution

Drop any check, referential, primary-key, or NOT NULL constraint on the surviving table, per the official guidance:
```
ALTER TABLE orders DROP CONSTRAINT ck_orders_status;
```
Attach the table, per the official guidance, once the constraints are cleared:
```
ALTER FRAGMENT ON TABLE orders ATTACH orders_2025;
```

Re-create the constraint afterward if still needed, per the official guidance:

ALTER TABLE orders ADD CONSTRAINT
  CHECK (status IN ('pending','shipped')) CONSTRAINT ck_orders_status;

Inventory every constraint on the surviving table before starting, since more than one type may be present:

SELECT constrname, constrtype FROM sysconstraints WHERE tabid =
  (SELECT tabid FROM systables WHERE tabname = 'orders');

Examples

Drop, attach, re-create

ALTER TABLE orders DROP CONSTRAINT ck_orders_status;
ALTER FRAGMENT ON TABLE orders ATTACH orders_2025;
ALTER TABLE orders ADD CONSTRAINT
  CHECK (status IN ('pending','shipped')) CONSTRAINT ck_orders_status;

Diagnostic Checks

Query sysconstraints for every constraint on the surviving table, and drop each one of the four affected types before attempting the attach.

Related Errors / Related Topics

-866 — "Cannot attach tables that contain serial fields." Same general family of ATTACH-prerequisite restrictions — drop or modify the blocking structure first.
-864 — "Cannot attach a table with rowids." Same family, for ROWID specifically.

Drop check, referential, primary-key, and NOT NULL constraints from the surviving table first, attach, then re-create the constraints afterward if still needed.