> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sqd.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# E2005

> ClickHouse target — Rollback table has no `sign` column

The table has no `sign` column, so cancel-row rollback cannot work.

**Fix** — add a `sign` column and use a `CollapsingMergeTree`-family engine for tables you roll back.