column "{colId}" cannot be served under ingest.dropSourceRows: it is an impure computed column (a shadow or a positional/rank column) that is never stored, so it can only be read from the caller's row objects

Warnings reference › source.dropped.*

Identifier

source.dropped.*

Raised by

The grid (core)

Since

1.17.0

What happened

ingest.dropSourceRows frees the original row objects once their values are columnised, and an impure computed column - a shadow, a rank, anything positional - is never stored, so it can only be read from the objects that are now gone. Rather than hand back a handle full of undefined and quietly sort, filter or total the grid to a wrong answer, no handle is returned at all and the caller drops the column through its usual unknown-column path.

The fix

Keep the source rows (ingest.dropSourceRows: false) if the column is needed, or drop the column.

Reference

Covered in full at the API reference.