diff options
Diffstat (limited to 'src/mongo/db/query/plan_enumerator.h')
| -rw-r--r-- | src/mongo/db/query/plan_enumerator.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/src/mongo/db/query/plan_enumerator.h b/src/mongo/db/query/plan_enumerator.h index c547573ce2e..20994eedba7 100644 --- a/src/mongo/db/query/plan_enumerator.h +++ b/src/mongo/db/query/plan_enumerator.h @@ -345,6 +345,31 @@ private: std::vector<MatchExpression*>* out); /** + * Assigns predicates from 'couldAssign' to 'indexAssignment' that can safely be assigned + * according to the intersecting and compounding rules for multikey indexes. The rules can + * loosely be stated as follows: + * + * - It is always safe to assign a predicate on path Y to the index when no prefix of the path + * Y causes the index to be multikey. + * + * - For any non-$elemMatch predicate on path X already assigned to the index, it isn't safe + * to assign a predicate on path Y (possibly equal to X) to the index when a shared prefix + * of the paths X and Y causes the index to be multikey. + * + * - For any $elemMatch predicate on path X already assigned to the index, it isn't safe to + * assign a predicate on path Y (possibly equal to X) to the index when + * (a) a shared prefix of the paths X and Y causes the index to be multikey and the + * predicates aren't joined by the same $elemMatch context, or + * (b) a shared prefix of the paths X and Y inside the innermost $elemMatch causes the + * index to be multikey. + * + * This function should only be called if the index has path-level multikey information. + * Otherwise, getMultikeyCompoundablePreds() and compound() should be used instead. + */ + void assignMultikeySafePredicates(const std::vector<MatchExpression*>& couldAssign, + OneIndexAssignment* indexAssignment); + + /** * 'andAssignment' contains assignments that we've already committed to outputting, * including both single index assignments and ixisect assignments. * |