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Informix Error -855

-855 Cannot drop rowids on a non-fragmented table.

You tried to use the ALTER TABLE...DROP syntax to drop the rowid column on a table that is not fragmented. A non-fragmented table has a rowid column, but you cannot drop it.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-855 fires when ALTER TABLE ... DROP ROWIDS (or the equivalent) is attempted on a non-fragmented table — per the official guidance, a non-fragmented table always has a ROWID column, and it can't be dropped from it.

  1. ALTER TABLE ... DROP targeting the ROWID column of a non-fragmented table, per the official guidance — the direct, only cause; ROWID is an intrinsic part of a non-fragmented table's structure.
  2. A misunderstanding of when ROWID can be dropped, per the official guidance's framing — the ability to drop ROWID is specific to fragmented tables (see -857), not available generally.
Solutions / Resolution
  1. Don't attempt to drop ROWID on a non-fragmented table — per the official guidance, this isn't supported under any circumstances; it's an intrinsic property of the table's structure.
  2. If ROWID genuinely needs to be dropped, fragment the table first, since that operation is only meaningful (and only possible, per -857) on a fragmented table.
Examples
The disallowed attempt
-- orders is a non-fragmented table
ALTER TABLE orders DROP ROWIDS;
-- -855: non-fragmented tables always have ROWID; it can't be dropped
Diagnostic Checks
  1. Confirm whether the table is fragmented before attempting to drop its ROWID column — this operation only applies to fragmented tables.
Related Errors / Related Topics
  • -856 — "Rowids already exist on table." A related ROWID-management error, about adding a ROWID that already exists rather than dropping one from a non-fragmented table.
  • -857 — "Rowids do not exist on table." A related ROWID-management error, about dropping a ROWID that doesn't currently exist on a fragmented table.

ROWID is intrinsic to non-fragmented tables and can't be dropped — this operation only applies to fragmented tables.