Function fetch

tempodb/encoding/vparquet5/block_traceql.go:1628–1644

fetch is the core logic for executing the given conditions against the parquet columns. The algorithm can be summarized as a hiearchy of iterators where we iterate related columns together and collect the results at each level into attributes, spans, and spansets. Each condition (.foo=bar) is pushe

(ctx context.Context, req traceql.FetchSpansRequest, pf *parquet.File, rowGroups []parquet.RowGroup, dc backend.DedicatedColumns)

//                                                            V

func fetch(ctx context.Context, req traceql.FetchSpansRequest, pf *parquet.File, rowGroups []parquet.RowGroup, dc backend.DedicatedColumns) (*spansetIterator, error) {
	iter, err := createAllIterator(ctx, nil, req.Conditions, req.AllConditions, req.StartTimeUnixNanos, req.EndTimeUnixNanos, rowGroups, pf, dc, false, req.TraceSampler, req.SpanSampler)
	if err != nil {
		return nil, fmt.Errorf("error creating iterator: %w", err)
	}

	if req.SecondPass != nil {
		iter = newBridgeIterator(newRebatchIterator(iter), req.SecondPass)

		iter, err = createAllIterator(ctx, iter, req.SecondPassConditions, false, 0, 0, rowGroups, pf, dc, req.SecondPassSelectAll, nil, nil)
		if err != nil {
			return nil, fmt.Errorf("error creating second pass iterator: %w", err)
		}
	}

	return newSpansetIterator(newRebatchIterator(iter)), nil
}

type categorizedConditions struct {
	span            []traceql.Condition