Informix Error -773

Reasons / Common Causes

-773 fires when ALTER FRAGMENT ... ADD a new fragment to an expression-based fragmentation strategy without supplying the new fragment's expression — per the official guidance, an expression is required for every fragment in this strategy.

1. ALTER FRAGMENT ... ADD a fragment with no expression clause, per the official guidance — the direct, only cause, on a table using expression-based fragmentation.
2. A REMAINDER-style addition attempted on a table that doesn't actually support a remainder fragment, confusing the syntax needed for expression-based fragmentation with the REMAINDER keyword's own (expression-less) usage.

Solutions / Resolution

1. Restate the statement to include a fragment expression, per the official guidance:

   ALTER FRAGMENT ON TABLE orders ADD FRAGMENT new_dbspace (region = 'west');
   

2. Confirm the table's actual fragmentation strategy before adding a fragment, since the required syntax differs between expression-based and other strategies (round-robin, per -774, takes no expression at all):

   SELECT partn, evaltext FROM sysfragments WHERE tabid =
     (SELECT tabid FROM systables WHERE tabname = 'orders') AND fragtype = 'T';
   -- review the fragmentation strategy for the table
   

Examples

The disallowed attempt

ALTER FRAGMENT ON TABLE orders ADD FRAGMENT new_dbspace;
-- -773: no expression supplied for an expression-based fragmentation strategy

Corrected

ALTER FRAGMENT ON TABLE orders ADD FRAGMENT new_dbspace (region = 'west');

Diagnostic Checks

1. Confirm the table's fragmentation strategy is expression-based, and supply a matching expression for the new fragment.

Related Errors / Related Topics

• -772 — "Record/key doesn't qualify for any table/index fragment." A related fragmentation error, about existing rows not matching any fragment expression rather than a new fragment missing its expression.
• -774 — "Cannot specify fragment expressions with a round-robin fragmentation." The mirror-image restriction: an expression supplied where the strategy doesn't take one.

Expression-based fragmentation requires an expression for every fragment — confirm the table's strategy first, since round-robin (per -774) takes none at all.