Informix Error -21515: Cannot perform online index build for attached indices

Reasons / Common Causes

-21515 fires when an online index build is requested for an attached index — per the official guidance, online index build is only allowed for detached and semi-detached indices.

1. Requesting an online index build for an attached index, per the official guidance — the direct, only cause.

Solutions / Resolution

1. Detach the index, or use a non-online build for attached indices, per the official guidance's implication — online build isn't supported for attached indices.

Examples

N/A

No specific triggering statement is documented beyond requesting an online build on an attached index.

Diagnostic Checks

1. Check whether the target index is attached, detached, or semi-detached, and use a non-online build if it's attached.

Related Errors / Related Topics

• -21522 — "No online index build possible." A related online-index-build restriction, general to the scenario rather than specifically attached indices.

An online index build was requested for an attached index, which isn't supported — only detached/semi-detached indices allow online build.