Informix Error -610: Index not allowed on TEXT or BYTE columns.

Reasons / Common Causes

-610 fires when CREATE INDEX names a TEXT/BYTE column — per the official guidance, these types have no defined lexical ordering, so the server has no way to sort or compare values of these types and therefore can't build an inverted index on them.

1. CREATE INDEX directly naming a TEXT/BYTE column — the direct, only cause.
2. An attempt to make BLOB content searchable via an ordinary index, without realizing the type itself doesn't support the comparison operations an index depends on.

Solutions / Resolution

1. Extract an ordered set of key values from the BLOB content into a separate column, per the official guidance, if the application understands the data well enough to define a meaningful ordering — then index that column instead.
2. Index a derived/summary column instead of the raw TEXT/BYTE column — for example, a hash, a prefix extracted at insert time, or a searchable summary field populated alongside the BLOB.
3. Don't attempt to index the TEXT/BYTE column itself under any circumstances, since the restriction is structural (no lexical ordering), not a size or configuration limit that can be worked around directly.

Examples

The disallowed attempt

CREATE INDEX idx_content ON documents (content);
-- -610: content is TEXT, which has no defined ordering to index

Indexing a derived column instead

ALTER TABLE documents ADD content_key VARCHAR(100);
-- populate content_key at the application level (e.g. a prefix or hash of the
-- BLOB's content, computed after reading it out through the locator), since
-- Informix has no built-in function that converts TEXT/BYTE directly into an
-- indexable type -- extracting a derived value needs application code or a
-- user-defined routine (DataBlade, Java UDR, or C UDR), not a built-in SQL
-- expression, given -608/-609's restriction on converting TEXT/BYTE at all.
CREATE INDEX idx_content_key ON documents (content_key);

Diagnostic Checks

1. Confirm the column named in the failing CREATE INDEX is actually declared TEXT/BYTE, and identify what property of that content the index was actually meant to support (exact match, prefix search, etc.) before designing a derived column to index instead.

Related Errors / Related Topics

No closely related error codes are cross-referenced for -610 in this set yet.

A structural limitation, not a configuration one — extract an orderable value into a separate column and index that instead of the raw TEXT/BYTE column.