func parseSuffix(aid, ns string, suffixFormat []ds.IndexColumn, suffix []byte, count int) (raw [][]byte, decoded []ds.Property) {
buf := serialize.Invertible(bytes.NewBuffer(suffix))
decoded = make([]ds.Property, len(suffixFormat))
raw = make([][]byte, len(suffixFormat))
err := error(nil)
for i := range decoded {
if count >= 0 && i >= count {
break
}
needInvert := suffixFormat[i].Descending
buf.SetInvert(needInvert)
decoded[i], err = serialize.ReadProperty(buf, serialize.WithoutContext, aid, ns)
memoryCorruption(err)
offset := len(suffix) - buf.Len()
raw[i] = suffix[:offset]
suffix = suffix[offset:]
if needInvert {
raw[i] = serialize.Invert(raw[i])
}
}
return
}
// GetBinaryBounds gets the binary encoding of the upper and lower bounds of
// the inequality filter on fq, if any is defined. If a bound does not exist,
// it is nil.
//
// NOTE: if fq specifies a descending sort order for the inequality, the bounds
// will be inverted, incremented, and flipped.
func GetBinaryBounds(fq *ds.FinalizedQuery) (lower, upper []byte) {
// Pick up the start/end range from the inequalities, if any.
//
// start and end in the reducedQuery are normalized so that `start >=
// X < end`. Because of that, we need to tweak the inequality filters
// contained in the query if they use the > or <= operators.
if ineqProp := fq.IneqFilterProp(); ineqProp != "" {
_, startOp, startV := fq.IneqFilterLow()
if startOp != "" {
lower = serialize.ToBytes(startV)
if startOp == ">" {
lower = increment(lower)
}
}
_, endOp, endV := fq.IneqFilterHigh()
if endOp != "" {
upper = serialize.ToBytes(endV)
if endOp == "<=" {
upper = increment(upper)
}
}
// The inequality is specified in natural (ascending) order in the query's
// Filter syntax, but the order information may indicate to use a descending
// index column for it. If that's the case, then we must invert, swap and
// increment the inequality endpoints.
//
// Invert so that the desired numbers are represented correctly in the index.
// Swap so that our iterators still go from >= start to < end.
// Increment so that >= and < get correctly bounded (since the iterator is
// still using natrual bytes ordering)
if fq.Orders()[0].Descending {
hi, lo := []byte(nil), []byte(nil)
if len(lower) > 0 {
lo = increment(serialize.Invert(lower))
}
if len(upper) > 0 {
hi = increment(serialize.Invert(upper))
}
upper, lower = lo, hi
}
}
return
}
// toComparableString computes the byte-sortable 'order' string for the given
// key/PropertyMap.
//
// * start/end are byte sequences which are the inequality bounds of the
// query, if any. These are a serialized datastore.Property. If the
// inequality column is inverted, then start and end are also inverted and
// swapped with each other.
// * order is the list of sort orders in the actual executing queries.
// * k / pm are the data to derive a sortable string for.
//
// The result of this function is the series of serialized properties, one per
// order column, which represent this key/pm's first entry in the composite
// index that would point to it (e.g. the one with `order` sort orders).
func toComparableString(start, end []byte, order []ds.IndexColumn, k *ds.Key, pm ds.PropertyMap) (row, key []byte) {
doCmp := true
soFar := []byte{}
ps := serialize.PropertyMapPartially(k, nil)
for _, ord := range order {
row, ok := ps[ord.Property]
if !ok {
if vals, ok := pm[ord.Property]; ok {
row = serialize.PropertySlice(vals)
}
}
sort.Sort(row)
foundOne := false
for _, serialized := range row {
if ord.Descending {
serialized = serialize.Invert(serialized)
}
if doCmp {
maybe := serialize.Join(soFar, serialized)
cmp := bytes.Compare(maybe, start)
if cmp >= 0 {
foundOne = true
soFar = maybe
doCmp = len(soFar) < len(start)
break
}
} else {
foundOne = true
soFar = serialize.Join(soFar, serialized)
break
}
}
if !foundOne {
return nil, nil
}
}
if end != nil && bytes.Compare(soFar, end) >= 0 {
return nil, nil
}
return soFar, ps["__key__"][0]
}
// generate generates a single iterDefinition for the given index.
func generate(q *reducedQuery, idx *indexDefinitionSortable, c *constraints) *iterDefinition {
def := &iterDefinition{
c: idx.coll,
start: q.start,
end: q.end,
}
toJoin := make([][]byte, len(idx.eqFilts))
for _, sb := range idx.eqFilts {
val := c.peel(sb.Property)
if sb.Descending {
val = serialize.Invert(val)
}
toJoin = append(toJoin, val)
}
def.prefix = serialize.Join(toJoin...)
def.prefixLen = len(def.prefix)
if q.eqFilters["__ancestor__"] != nil && !idx.hasAncestor() {
// The query requires an ancestor, but the index doesn't explicitly have it
// as part of the prefix (otherwise it would have been the first eqFilt
// above). This happens when it's a builtin index, or if it's the primary
// index (for a kindless query), or if it's the Kind index (for a filterless
// query).
//
// builtin indexes are:
// Kind/__key__
// Kind/Prop/__key__
// Kind/Prop/-__key__
if len(q.suffixFormat) > 2 || q.suffixFormat[len(q.suffixFormat)-1].Property != "__key__" {
// This should never happen. One of the previous validators would have
// selected a different index. But just in case.
impossible(fmt.Errorf("cannot supply an implicit ancestor for %#v", idx))
}
// get the only value out of __ancestor__
anc, _ := q.eqFilters["__ancestor__"].Peek()
// Intentionally do NOT update prefixLen. This allows multiIterator to
// correctly include the entire key in the shared iterator suffix, instead
// of just the remainder.
// chop the terminal null byte off the q.ancestor key... we can accept
// anything which is a descendant or an exact match. Removing the last byte
// from the key (the terminating null) allows this trick to work. Otherwise
// it would be a closed range of EXACTLY this key.
chopped := []byte(anc[:len(anc)-1])
if q.suffixFormat[0].Descending {
chopped = serialize.Invert(chopped)
}
def.prefix = serialize.Join(def.prefix, chopped)
// Update start and end, since we know that if they contain anything, they
// contain values for the __key__ field. This is necessary because bytes
// are shifting from the suffix to the prefix, and start/end should only
// contain suffix (variable) bytes.
if def.start != nil {
if !bytes.HasPrefix(def.start, chopped) {
// again, shouldn't happen, but if it does, we want to know about it.
impossible(fmt.Errorf(
"start suffix for implied ancestor doesn't start with ancestor! start:%v ancestor:%v",
def.start, chopped))
}
def.start = def.start[len(chopped):]
}
if def.end != nil {
if !bytes.HasPrefix(def.end, chopped) {
impossible(fmt.Errorf(
"end suffix for implied ancestor doesn't start with ancestor! end:%v ancestor:%v",
def.end, chopped))
}
def.end = def.end[len(chopped):]
}
}
return def
}