SigNoz/signoz · warning · model.ApiError

removing a selected field is not allowed, please reach out t

Error message

removing a selected field is not allowed, please reach out to support.

What it means

UpdateLogField refuses requests where field.Selected is false — once a log field column has been materialized/selected in ClickHouse, unselecting it via the API is not allowed and requires support intervention.

Source

Thrown at pkg/query-service/app/clickhouseReader/reader.go:2691

		if overrideFieldType != "" {
			field.Type = overrideFieldType
		}
		// all static fields are assumed to be selected as we don't allow changing them
		if isColumn(tableStatement, field.Type, field.Name, field.DataType) {
			response.Selected = append(response.Selected, field)
		} else {
			response.Interesting = append(response.Interesting, field)
		}
	}
}

func (r *ClickHouseReader) UpdateLogField(ctx context.Context, field *model.UpdateField) *model.ApiError {
	ctx = ctxtypes.NewContextWithCommentVals(ctx, map[string]string{
		instrumentationtypes.CodeNamespace:    "clickhouse-reader",
		instrumentationtypes.CodeFunctionName: "UpdateLogField",
	})
	if !field.Selected {
		return model.ForbiddenError(errors.New("removing a selected field is not allowed, please reach out to support."))
	}

	colname := utils.GetClickhouseColumnNameV2(field.Type, field.DataType, field.Name)

	field.DataType = strings.ToLower(field.DataType)
	dataType := constants.MaterializedDataTypeMap[field.DataType]
	chDataType := constants.ChDataTypeMap[field.DataType]

	attrColName := fmt.Sprintf("%s_%s", field.Type, dataType)
	for _, table := range []string{r.logsLocalTableV2, r.logsTableV2} {
		q := "ALTER TABLE %s.%s ON CLUSTER %s ADD COLUMN IF NOT EXISTS `%s` %s DEFAULT %s['%s'] CODEC(ZSTD(1))"
		query := fmt.Sprintf(q,
			r.logsDB, table,
			r.cluster,
			colname, chDataType,
			attrColName,
			field.Name,
		)

View on GitHub (pinned to 5069bf80b0)

Solutions

1. Reach out to support to unselect/materialize-column removal for log fields
2. Instead of unselecting, adjust which fields you select going forward and stop adding new ones
3. Review selected fields carefully before enabling them, since the operation is effectively irreversible via API

Example fix

// before
{"type":"log","name":"user.id","dataType":"string","selected":false}
// after
// (no API fix — contact support; avoid unselecting already-selected fields)

if !field.Selected && wasPreviouslySelected(field) {
    return errors.New("unsupported", "unselecting selected fields requires support")
}

func isUnselectRequest(f *model.UpdateField) bool { return f != nil && !f.Selected }

if apiErr := updateLogField(ctx, field); apiErr != nil && apiErr.IsForbidden() {
    // surface 'contact support' message
}

When it happens

Trigger: PUT/PATCH to the update-log-field endpoint with {"selected": false} in the body.

Common situations: Users trying to reduce cardinally materialized columns from the UI; cleanup attempts after accidentally selecting too many fields.

Related errors

• error while fetching logs schema: %s
• no operations table supplied
• no index table supplied
• couldn't get attribute keys: %w
• couldn't query attrib values for suggestions: %w

AI-assisted analysis of SigNoz/signoz@5069bf80b0 (2026-08-28). Data as JSON: /api/errors/a8192068983dd7f6. Report an issue: GitHub.