Golang IndexDefinition.Builtin方法代码示例

// maybeAddDefinition possibly adds a new IndexDefinitionSortable to this slice.
// It's only added if it could be useful in servicing q, otherwise this function
// is a noop.
//
// This returns true iff the proposed index is OK and depletes missingTerms to
// empty.
//
// If the proposed index is PERFECT (e.g. contains enough columns to cover all
// equality filters, and also has the correct suffix), idxs will be replaced
// with JUST that index, and this will return true.
func (idxs *IndexDefinitionSortableSlice) maybeAddDefinition(q *reducedQuery, s *memStore, missingTerms stringSet, id *ds.IndexDefinition) bool {
	// Kindless queries are handled elsewhere.
	if id.Kind != q.kind {
		impossible(
			fmt.Errorf("maybeAddDefinition given index with wrong kind %q v %q", id.Kind, q.kind))
	}

	// If we're an ancestor query, and the index is compound, but doesn't include
	// an Ancestor field, it doesn't work. Builtin indexes can be used for
	// ancestor queries (and have !Ancestor), assuming that it's only equality
	// filters (plus inequality on __key__), or a single inequality.
	if q.eqFilters["__ancestor__"] != nil && !id.Ancestor && !id.Builtin() {
		impossible(
			fmt.Errorf("maybeAddDefinition given compound index with wrong ancestor info: %s %#v", id, q))
	}

	// add __ancestor__ if necessary
	sortBy := id.GetFullSortOrder()

	// If the index has fewer fields than we need for the suffix, it can't
	// possibly help.
	if len(sortBy) < len(q.suffixFormat) {
		return false
	}

	numEqFilts := len(sortBy) - len(q.suffixFormat)
	// make sure the orders are precisely the same
	for i, sb := range sortBy[numEqFilts:] {
		if q.suffixFormat[i] != sb {
			return false
		}
	}

	if id.Builtin() && numEqFilts == 0 {
		if len(q.eqFilters) > 1 || (len(q.eqFilters) == 1 && q.eqFilters["__ancestor__"] == nil) {
			return false
		}
	}

	// Make sure the equalities section doesn't contain any properties we don't
	// want in our query.
	//
	// numByProp && totalEqFilts will be used to see if this is a perfect match
	// later.
	numByProp := make(map[string]int, len(q.eqFilters))
	totalEqFilts := 0

	eqFilts := sortBy[:numEqFilts]
	for _, p := range eqFilts {
		if _, ok := q.eqFilters[p.Property]; !ok {
			return false
		}
		numByProp[p.Property]++
		totalEqFilts++
	}

	// ok, we can actually use this

	// Grab the collection for convenience later. We don't want to invalidate this
	// index's potential just because the collection doesn't exist. If it's
	// a builtin and it doesn't exist, it still needs to be one of the 'possible'
	// indexes... it just means that the user's query will end up with no results.
	coll := s.GetCollection(
		fmt.Sprintf("idx:%s:%s", q.ns, serialize.ToBytes(*id.PrepForIdxTable())))

	// First, see if it's a perfect match. If it is, then our search is over.
	//
	// A perfect match contains ALL the equality filter columns (or more, since
	// we can use residuals to fill in the extras).
	toAdd := IndexDefinitionSortable{coll: coll}
	toAdd.eqFilts = eqFilts
	for _, sb := range toAdd.eqFilts {
		missingTerms.rm(sb.Property)
	}

	perfect := false
	if len(sortBy) == q.numCols {
		perfect = true
		for k, num := range numByProp {
			if num < len(q.eqFilters[k]) {
				perfect = false
				break
			}
		}
	}
	if perfect {
		*idxs = IndexDefinitionSortableSlice{toAdd}
	} else {
		*idxs = append(*idxs, toAdd)
	}
//.........这里部分代码省略.........