Informix Error -780

Reasons / Common Causes

-780 fires when ALTER FRAGMENT (a modification requiring an existing fragmentation scheme, such as DETACH, MODIFY, or naming a specific partition) targets a table/index that was never fragmented in the first place — per the official guidance, the operation simply doesn't apply.

1. ALTER FRAGMENT targeting a table/index that has only a single, unfragmented storage location, per the official guidance — the direct, only cause.
2. DDL copy-pasted from a fragmented table's maintenance script, applied to a different, unfragmented table by mistake.

Solutions / Resolution

1. Fragment the table or index first, per the official guidance, if fragmentation was genuinely intended for this table:

   ALTER FRAGMENT ON TABLE orders INIT FRAGMENT BY EXPRESSION
     (region = 'east') IN east_dbspace, (region = 'west') IN west_dbspace;
   

2. Or don't perform the fragmentation-specific operation, per the official guidance, if the table genuinely isn't meant to be fragmented.

Examples

The disallowed attempt

-- orders has no fragmentation scheme
ALTER FRAGMENT ON TABLE orders DETACH east_partition new_table_name;
-- -780: orders isn't fragmented, so there's no partition to detach

Corrected — establish fragmentation first, if that was the actual goal

ALTER FRAGMENT ON TABLE orders INIT FRAGMENT BY EXPRESSION
  (region = 'east') IN east_dbspace, (region = 'west') IN west_dbspace;

Diagnostic Checks

1. Confirm the table/index actually has a fragmentation scheme before attempting an operation that requires one:

   SELECT partn FROM sysfragments WHERE tabid =
     (SELECT tabid FROM systables WHERE tabname = 'orders') AND fragtype = 'T';
   -- no rows returned means the table isn't fragmented
   

Related Errors / Related Topics

• -781 — "Cannot alter fragmentation on a temp table." A related ALTER FRAGMENT restriction, specific to temp tables rather than tables that simply were never fragmented.

Confirm the table/index actually has a fragmentation scheme before attempting an operation that requires one.