/**
* Traverse the subtree rooted at 'node' to remove invalid RelevantTag assignments to text index
* 'idx', which has prefix paths 'prefixPaths'.
*/
static void stripInvalidAssignmentsToTextIndex(MatchExpression* node,
size_t idx,
const unordered_set<StringData, StringData::Hasher>& prefixPaths) {
// If we're here, there are prefixPaths and node is either:
// 1. a text pred which we can't use as we have nothing over its prefix, or
// 2. a non-text pred which we can't use as we don't have a text pred AND-related.
if (Indexability::nodeCanUseIndexOnOwnField(node)) {
removeIndexRelevantTag(node, idx);
return;
}
// Do not traverse tree beyond negation node.
if (node->matchType() == MatchExpression::NOT
|| node->matchType() == MatchExpression::NOR) {
return;
}
// For anything to use a text index with prefixes, we require that:
// 1. The text pred exists in an AND,
// 2. The non-text preds that use the text index's prefixes are also in that AND.
if (node->matchType() != MatchExpression::AND) {
// It's an OR or some kind of array operator.
for (size_t i = 0; i < node->numChildren(); ++i) {
stripInvalidAssignmentsToTextIndex(node->getChild(i), idx, prefixPaths);
}
return;
}
// If we're here, we're an AND. Determine whether the children satisfy the index prefix for
// the text index.
invariant(node->matchType() == MatchExpression::AND);
bool hasText = false;
// The AND must have an EQ predicate for each prefix path. When we encounter a child with a
// tag we remove it from childrenPrefixPaths. All children exist if this set is empty at
// the end.
unordered_set<StringData, StringData::Hasher> childrenPrefixPaths = prefixPaths;
for (size_t i = 0; i < node->numChildren(); ++i) {
MatchExpression* child = node->getChild(i);
RelevantTag* tag = static_cast<RelevantTag*>(child->getTag());
if (NULL == tag) {
// 'child' could be a logical operator. Maybe there are some assignments hiding
// inside.
stripInvalidAssignmentsToTextIndex(child, idx, prefixPaths);
continue;
}
bool inFirst = tag->first.end() != std::find(tag->first.begin(),
tag->first.end(),
idx);
bool inNotFirst = tag->notFirst.end() != std::find(tag->notFirst.begin(),
tag->notFirst.end(),
idx);
if (inFirst || inNotFirst) {
// Great! 'child' was assigned to our index.
if (child->matchType() == MatchExpression::TEXT) {
hasText = true;
}
else {
childrenPrefixPaths.erase(child->path());
// One fewer prefix we're looking for, possibly. Note that we could have a
// suffix assignment on the index and wind up here. In this case the erase
// above won't do anything since a suffix isn't a prefix.
}
}
else {
// Recurse on the children to ensure that they're not hiding any assignments
// to idx.
stripInvalidAssignmentsToTextIndex(child, idx, prefixPaths);
}
}
// Our prereqs for using the text index were not satisfied so we remove the assignments from
// all children of the AND.
if (!hasText || !childrenPrefixPaths.empty()) {
for (size_t i = 0; i < node->numChildren(); ++i) {
stripInvalidAssignmentsToTextIndex(node->getChild(i), idx, prefixPaths);
}
}
}
static void stripInvalidAssignmentsTo2dsphereIndex(MatchExpression* node, size_t idx) {
if (Indexability::nodeCanUseIndexOnOwnField(node)) {
removeIndexRelevantTag(node, idx);
return;
}
const MatchExpression::MatchType nodeType = node->matchType();
// Don't bother peeking inside of negations.
if (MatchExpression::NOT == nodeType || MatchExpression::NOR == nodeType) {
return;
}
if (MatchExpression::AND != nodeType) {
// It's an OR or some kind of array operator.
for (size_t i = 0; i < node->numChildren(); ++i) {
stripInvalidAssignmentsTo2dsphereIndex(node->getChild(i), idx);
}
return;
}
bool hasGeoField = false;
for (size_t i = 0; i < node->numChildren(); ++i) {
MatchExpression* child = node->getChild(i);
RelevantTag* tag = static_cast<RelevantTag*>(child->getTag());
if (NULL == tag) {
// 'child' could be a logical operator. Maybe there are some assignments hiding
// inside.
stripInvalidAssignmentsTo2dsphereIndex(child, idx);
continue;
}
bool inFirst = tag->first.end() != std::find(tag->first.begin(),
tag->first.end(),
idx);
bool inNotFirst = tag->notFirst.end() != std::find(tag->notFirst.begin(),
tag->notFirst.end(),
idx);
// If there is an index assignment...
if (inFirst || inNotFirst) {
// And it's a geo predicate...
if (MatchExpression::GEO == child->matchType() ||
MatchExpression::GEO_NEAR == child->matchType()) {
hasGeoField = true;
}
}
else {
// Recurse on the children to ensure that they're not hiding any assignments
// to idx.
stripInvalidAssignmentsTo2dsphereIndex(child, idx);
}
}
// If there isn't a geo predicate our results aren't a subset of what's in the geo index, so
// if we use the index we'll miss results.
if (!hasGeoField) {
for (size_t i = 0; i < node->numChildren(); ++i) {
stripInvalidAssignmentsTo2dsphereIndex(node->getChild(i), idx);
}
}
}
