Function createAttributeIterator

tempodb/encoding/vparquet4/block_traceql.go:2981–3106

(makeIter makeIterFn, conditions []traceql.Condition,
	definitionLevel int,
	keyPath, strPath, intPath, floatPath, boolPath string,
	allConditions bool, selectAll bool,
)

}

func createAttributeIterator(makeIter makeIterFn, conditions []traceql.Condition,
	definitionLevel int,
	keyPath, strPath, intPath, floatPath, boolPath string,
	allConditions bool, selectAll bool,
) (parquetquery.Iterator, error) {
	skipNils := &parquetquery.SkipNilsPredicate{}

	if selectAll {
		// Select all with no filtering
		// Levels such as resource/instrumentation/span may have no attributes. When that
		// occurs the columns are encoded as single null values, and the current attribute
		// collector reads them as Nils.  We could skip them in the attribute collector,
		// but this is more performant because it's at the lowest level.
		// Alternatively, JoinIterators don't pay attention to -1 (undefined) when checking
		// the definition level matches.  Fixing that would also work but would need wider testing first.
		return parquetquery.NewLeftJoinIterator(definitionLevel,
			[]parquetquery.Iterator{
				makeIter(keyPath, skipNils, "key"),
			},
			[]parquetquery.Iterator{
				makeIter(strPath, skipNils, "string"),
				makeIter(intPath, skipNils, "int"),
				makeIter(floatPath, skipNils, "float"),
				makeIter(boolPath, skipNils, "bool"),
			},
			&attributeCollector{},
			parquetquery.WithPool(pqAttrPool))
	}

	var (
		attrKeys        = []string{}
		attrStringPreds = []parquetquery.Predicate{}
		attrIntPreds    = []parquetquery.Predicate{}
		attrFltPreds    = []parquetquery.Predicate{}
		boolPreds       = []parquetquery.Predicate{}
	)
	for _, cond := range conditions {

		attrKeys = append(attrKeys, cond.Attribute.Name)

		switch cond.Op {
		case traceql.OpNone:
			// This means we have to scan all value columns since we don't know what type
			// to expect.  No filtering.
			attrStringPreds = append(attrStringPreds, nil)
			attrIntPreds = append(attrIntPreds, nil)
			attrFltPreds = append(attrFltPreds, nil)
			boolPreds = append(boolPreds, nil)
			continue
		case traceql.OpExists:
			// Similarly scan all value types, but we can skip nils.
			attrStringPreds = append(attrStringPreds, skipNils)
			attrIntPreds = append(attrIntPreds, skipNils)
			attrFltPreds = append(attrFltPreds, skipNils)
			boolPreds = append(boolPreds, skipNils)
			continue
		}