diff options
Diffstat (limited to 'src/mongo/s/shard_key_pattern.h')
| -rw-r--r-- | src/mongo/s/shard_key_pattern.h | 35 |
1 files changed, 17 insertions, 18 deletions
diff --git a/src/mongo/s/shard_key_pattern.h b/src/mongo/s/shard_key_pattern.h index 70f5aff336d..545d1906e31 100644 --- a/src/mongo/s/shard_key_pattern.h +++ b/src/mongo/s/shard_key_pattern.h @@ -274,37 +274,36 @@ public: BSONObj extractShardKeyFromQuery(const CanonicalQuery& query) const; /** - * Returns true if the shard key pattern can ensure that the index uniqueness is respected - * across all shards. + * Returns true if the shard key pattern can ensure that the unique index pattern is + * respected across all shards. * * Primarily this just checks whether the shard key pattern field names are equal to or a - * prefix of the 'unique' or 'prepareUnique' index pattern field names. Since documents with the - * same fields in the shard key pattern are guaranteed to go to the same shard, and all - * documents must contain the full shard key, an index with {unique: true} or {prepareUnique: - * true} and a shard key pattern prefix can be sure when resolving duplicates that documents on - * other shards will have different shard keys, and so are not duplicates. + * prefix of the unique index pattern field names. Since documents with the same fields in + * the shard key pattern are guaranteed to go to the same shard, and all documents must + * contain the full shard key, a unique index with a shard key pattern prefix can be sure + * when resolving duplicates that documents on other shards will have different shard keys, + * and so are not duplicates. * * Hashed shard key patterns are similar to ordinary patterns in that they guarantee similar * shard keys go to the same shard. * * Examples: - * shard key {a : 1} is compatible with a unique/prepareUnique index on {_id : 1} - * shard key {a : 1} is compatible with a unique/prepareUnique index on {a : 1, b : 1} - * shard key {a : 1} is compatible with a unique/prepareUnique index on {a : -1, b : 1} - * shard key {a : "hashed"} is compatible with a unique/prepareUnique index on {a : 1} - * shard key {a : 1} is not compatible with a unique/prepareUnique index on {b : 1} - * shard key {a : "hashed", b : 1} is not compatible with unique/prepareUnique index on - * {b : 1} + * shard key {a : 1} is compatible with a unique index on {_id : 1} + * shard key {a : 1} is compatible with a unique index on {a : 1 , b : 1} + * shard key {a : 1} is compatible with a unique index on {a : -1 , b : 1 } + * shard key {a : "hashed"} is compatible with a unique index on {a : 1} + * shard key {a : 1} is not compatible with a unique index on {b : 1} + * shard key {a : "hashed" , b : 1 } is not compatible with unique index on { b : 1 } * * All unique index patterns starting with _id are assumed to be enforceable by the fact * that _ids must be unique, and so all unique _id prefixed indexes are compatible with * any shard key pattern. * - * NOTE: We assume 'indexPattern' is a valid unique/prepareUnique index pattern - a pattern like - * { k : "hashed" } is not capable of being a unique/prepareUnique index and is an invalid - * argument to this method. + * NOTE: We assume 'uniqueIndexPattern' is a valid unique index pattern - a pattern like + * { k : "hashed" } is not capable of being a unique index and is an invalid argument to + * this method. */ - bool isIndexUniquenessCompatible(const BSONObj& indexPattern) const; + bool isUniqueIndexCompatible(const BSONObj& uniqueIndexPattern) const; /** * Return an ordered list of bounds generated using this KeyPattern and the |