> ## 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.

# E2004

> ClickHouse target — Rollback engine collapses on the wrong column

The table's collapsing engine collapses on a column other than `sign`. Rollback inserts cancel rows
with `sign = -1`, so the collapse column must be named `sign`.

**Fix** — rename the collapse column to `sign`.