Function fetch

packages/db/src/engine/fetch.ts:13–148

(plan: Plan)

 * This handles breakdown expansion automatically via groupByLabels
 */
export async function fetch(plan: Plan): Promise<ConcreteSeries[]> {
  const results: ConcreteSeries[] = [];

  // Process each event definition
  for (let i = 0; i < plan.definitions.length; i++) {
    const definition = plan.definitions[i]!;

    if (definition.type !== 'event') {
      // Skip formulas - they'll be handled in compute stage
      continue;
    }

    const event = definition as typeof definition & { type: 'event' };

    // Find the corresponding concrete series placeholder
    const placeholder = plan.concreteSeries.find(
      (cs) => cs.definitionId === definition.id,
    );

    if (!placeholder) {
      continue;
    }

    // Build query input
    const queryInput: IGetChartDataInput = {
      event: {
        id: event.id,
        name: event.name,
        segment: event.segment,
        filters: event.filters,
        displayName: event.displayName,
        property: event.property,
      },
      projectId: plan.input.projectId,
      startDate: plan.input.startDate,
      endDate: plan.input.endDate,
      breakdowns: plan.input.breakdowns,
      interval: plan.input.interval,
      chartType: plan.input.chartType,
      metric: plan.input.metric,
      previous: plan.input.previous ?? false,
      limit: plan.input.limit,
      offset: plan.input.offset,
    };

    // Execute query
    let queryResult = await chQuery<ISerieDataItem>(
      await getChartSql({ ...queryInput, timezone: plan.timezone }),
      {
        session_timezone: plan.timezone,
      },
    );

    // Fallback: if no results with breakdowns, try without breakdowns
    if (queryResult.length === 0 && plan.input.breakdowns.length > 0) {
      queryResult = await chQuery<ISerieDataItem>(
        await getChartSql({
          ...queryInput,