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Informix Error -712

-712 Cannot insert encoded BLOB descriptor in non-optical BLOB columns.

You have attempted to use the DESCR() function to insert an encoded blob descriptor into a TEXT or BYTE column that is stored in a dbspace or blobspace. You can use this function only to insert descriptors into blob columns that are stored on optical media.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-712 fires when DESCR() is used to insert an encoded BLOB descriptor into a TEXT/BYTE column stored in an ordinary dbspace/blobspace — per the official guidance, DESCR() can only insert into BLOB columns stored on optical media, the same optical-vs-ordinary-storage distinction as -638/-644.

  1. DESCR() targeting a TEXT/BYTE column stored in an ordinary storage space rather than on optical media, per the official guidance — the direct, only cause.
  2. A column-naming mistake, targeting the wrong TEXT/BYTE column, one stored in an ordinary storage space rather than the intended optical one.
Solutions / Resolution
  1. Check that the target column is stored on optical media, per the official guidance, before using DESCR() to insert into it.
  2. Confirm the column's storage space the same way as for -638:
    SELECT colname FROM syscolumns
WHERE tabid = (SELECT tabid FROM systables WHERE tabname = 'documents');
    combined with reviewing the CREATE TABLE's original storage-space clause for that column.
  3. If the data genuinely needs to live in an ordinary storage space, don't use DESCR() — insert the actual BLOB content directly instead of an encoded descriptor.
Examples
The disallowed attempt
-- content is TEXT, stored in an ordinary blobspace (not optical media)
INSERT INTO documents (doc_id, content) VALUES (1, DESCR('family1', 3, 'some description'));
-- -712: content isn't on optical media
Diagnostic Checks
  1. Review the target column's storage-space clause, confirming whether it's optical media or an ordinary storage space, the same check as -638.
Related Errors / Related Topics
  • -638 — "Cannot cluster TEXT or BYTE columns on non-optical media." The same underlying optical-vs-ordinary-storage distinction, in the CREATE OPTICAL CLUSTER context.
  • -711 — "Cannot insert encoded BLOB descriptor." The more general DESCR()-insert failure, of which this is a specific, named case.

The same optical-vs-ordinary-storage distinction as -638 — confirm the target column's actual storage space before using DESCR().