2dsphere Indexes索引

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Overview概述

A 2dsphere index supports queries that calculate geometries on an earth-like sphere. 2dsphere索引支持计算类地球球体上的几何图形的查询。2dsphere index supports all MongoDB geospatial queries: queries for inclusion, intersection and proximity. 2dsphere索引支持所有MongoDB地理空间查询：包含查询、交集查询和邻近查询。For more information on geospatial queries, see Geospatial Queries.有关地理空间查询的详细信息，请参阅地理空间查询。

The 2dsphere index supports data stored as GeoJSON objects and legacy coordinate pairs (See also 2dsphere Indexed Field Restrictions). 2dsphere索引支持存储为GeoJSON对象和传统坐标对的数据（另请参见2dsphere索引字段限制）。For legacy coordinate pairs, the index converts the data to GeoJSON Point.对于传统坐标对，索引将数据转换为GeoJSON点。

Versions

2dsphere Index Version索引版本Description描述
Version 3 MongoDB 3.2 introduces a version 3 of 2dsphere indexes. MongoDB 3.2引入了2dsphere索引的第3版。Version 3 is the default version of 2dsphere indexes created in MongoDB 3.2 and later.版本3是在MongoDB 3.2及更高版本中创建的2dsphere索引的默认版本。
Version 2 MongoDB 2.6 introduces a version 2 of 2dsphere indexes. MongoDB 2.6引入了2dsphere索引的第2版。Version 2 is the default version of 2dsphere indexes created in MongoDB 2.6 and 3.0 series.版本2是在MongoDB 2.6和3.0系列中创建的2dsphere索引的默认版本。

To override the default version and specify a different version, include the option { "2dsphereIndexVersion": <version> } when creating the index.要覆盖默认版本并指定其他版本，请在创建索引时包含选项{ "2dsphereIndexVersion": <version> }。

sparse Property

Version 2 and later 2dsphere indexes are always sparse and ignore the sparse option. 版本2和更高版本的2dsphere索引始终是稀疏的，忽略sparse选项。If a document lacks a 2dsphere index field (or the field is null or an empty array), MongoDB does not add an entry for the document to the index. 如果文档缺少2dsphere索引字段（或字段为null或空数组），MongoDB不会将文档条目添加到索引中。For inserts, MongoDB inserts the document but does not add to the 2dsphere index.对于插入，MongoDB会插入文档，但不会添加到2dsphere索引中。

For a compound index that includes a 2dsphere index key along with keys of other types, only the 2dsphere index field determines whether the index references a document.对于包含2dsphere索引键和其他类型键的复合索引，只有2dsphere索引字段确定索引是否引用文档。

Earlier versions of MongoDB only support 2dsphere (Version 1) indexes. 早期版本的MongoDB只支持2dsphere (Version 1)索引。2dsphere (Version 1) indexes are not sparse by default and will reject documents with null location fields.默认情况下，2dsphere (Version 1)索引不是稀疏的，将拒绝包含null位置字段的文档。

Additional GeoJSON Objects其他GeoJSON对象

Version 2 and later 2dsphere indexes includes support for additional GeoJSON object: MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection. 版本2及更高版本的2dsphere索引包括对附加GeoJSON对象的支持：多点、多线、多多边形和GeometryCollection。For details on all supported GeoJSON objects, see GeoJSON Objects.有关所有受支持的GeoJSON对象的详细信息，请参阅GeoJSON对象。

Considerations考虑事项

geoNear and $geoNear RestrictionsgeoNear和$geoNear限制

Starting in MongoDB 4.0, you can specify a key option to the $geoNear pipeline stage to indicate the indexed field path to use. 从MongoDB 4.0开始，您可以为$geoNear管道阶段指定一个key选项，以指示要使用的索引字段路径。This allows the $geoNear stage to be used on a collection that has multiple 2dsphere index and/or multiple 2d index:这允许$geoNear阶段用于具有多个2dsphere索引和/或多个2d索引的集合：

  • If your collection has multiple 2dsphere index and/or multiple 2d index, you must use the key option to specify the indexed field path to use.如果集合有多个2dsphere索引和/或多个2d索引，则必须使用key选项指定要使用的索引字段路径。
  • If you do not specify the key, you cannot have multiple 2dsphere index and/or multiple 2d index since without the key, index selection among multiple 2d indexes or 2dsphere indexes is ambiguous.如果不指定key，则不能有多个2dsphere索引和/或多个2d索引，因为没有key，多个2d索引或2dsphere索引之间的索引选区是不明确的。

Note

If you do not specify the key, and you have at most only one 2dsphere index index and/or only one 2dsphere index index, MongoDB looks first for a 2d index to use. 如果不指定key，并且最多只有一个2dsphere索引和/或一个2dsphere索引，MongoDB会首先查找要使用的二维索引。If a 2d index does not exists, then MongoDB looks for a 2dsphere index to use.如果2d索引不存在，则MongoDB会查找要使用的2dsphere索引。

Shard Key Restrictions分片密钥限制

You cannot use a 2dsphere index as a shard key when sharding a collection. 切分集合时，不能将2dsphere索引用作 切分键。However, you can create a geospatial index on a sharded collection by using a different field as the shard key.但是，可以使用其他字段作为分片键，在分片集合上创建地理空间索引。

2dsphere Indexed Field Restrictions索引字段限制

Fields with 2dsphere indexes must hold geometry data in the form of coordinate pairs or GeoJSON data. 具有2dsphere索引的字段必须以坐标对或GeoJSON数据的形式保存几何体数据。If you attempt to insert a document with non-geometry data in a 2dsphere indexed field, or build a 2dsphere index on a collection where the indexed field has non-geometry data, the operation will fail.如果试图在2dsphere索引字段中插入包含非几何体数据的文档，或在索引字段包含非几何体数据的集合上构建2dsphere索引，则操作将失败。

Create a 2dsphere Index创建一个2dsphere索引

To create a 2dsphere index, use the db.collection.createIndex() method and specify the string literal "2dsphere" as the index type:要创建2dsphere索引，请使用db.collection.createIndex()方法，并将字符串文本"2dsphere"指定为索引类型：

db.collection.createIndex( { <location field> : "2dsphere" } )

where the <location field> is a field whose value is either a GeoJSON object or a legacy coordinates pair.其中，<location field>是一个值为GeoJSON对象或遗留坐标对的字段。

Unlike a compound 2d index which can reference one location field and one other field, a compound 2dsphere index can reference multiple location and non-location fields.与可以引用一个位置字段和另一个字段的复合2d索引不同，复合2dsphere索引可以引用多个位置字段和非位置字段。

For the following examples, consider a collection places with documents that store location data as GeoJSON Point in a field named loc:对于下面的示例，考虑一个集合位置，这些文档将存储位置数据作为GeoJSON点存储在一个名为loc的字段中：

db.places.insert(
   {
      loc : { type: "Point", coordinates: [ -73.97, 40.77 ] },
      name: "Central Park",
      category : "Parks"
   }
)

db.places.insert(
   {
      loc : { type: "Point", coordinates: [ -73.88, 40.78 ] },
      name: "La Guardia Airport",
      category : "Airport"
   }
)

Create a 2dsphere Index创建一个2dsphere索引

The following operation creates a 2dsphere index on the location field loc:以下操作在位置字段loc上创建一个2dsphere索引：

db.places.createIndex( { loc : "2dsphere" } )

Create a Compound Index with 2dsphere Index Key使用2dsphere索引键创建复合索引

A compound index can include a 2dsphere index key in combination with non-geospatial index keys. 复合索引可以包括2dsphere索引键和非地理空间索引键。For example, the following operation creates a compound index where the first key loc is a 2dsphere index key, and the remaining keys category and names are non-geospatial index keys, specifically descending (-1) and ascending (1) keys respectively.例如，下面的操作创建了一个复合索引，其中第一个键loc是2dsphere索引键，其余的键类别和名称是非地理空间索引键，分别是降序键（-1）和升序键（1）。

db.places.createIndex( { loc : "2dsphere" , category : -1, name: 1 } )

Unlike the 2d index, a compound 2dsphere index does not require the location field to be the first field indexed. 与 2d索引不同，复合2dsphere索引不需要将位置字段作为第一个索引字段。For example:例如：

db.places.createIndex( { category : 1 , loc : "2dsphere" } )