geoSearch
geoSearch-
The
geoSearchcommand provides an interface to MongoDB’s haystack index functionality. These indexes are useful for returning results based on location coordinates after collecting results based on some other query (i.e. a “haystack.”)The
geoSearchcommand accepts a document that contains the following fields.Field Type Description geoSearchstring The collection to query. searchdocument Query to filter documents. neararray Coordinates of a point. maxDistancenumber Optional. Maximum distance from the specified point. limitnumber Optional. Maximum number of documents to return. readConcerndocument Optional. Specifies the read concern.
The readConcern option has the following syntax:
Changed in version 3.6.
readConcern: { level: <value> }Possible read concern levels are:
"local". This is the default read concern level."available". This is the default for reads against secondaries when Read Operations and Causally Consistent Sessions and “level” are unspecified. The query returns the instance’s most recent data."majority". Available for replica sets that use WiredTiger storage engine."linearizable". Available for read operations on theprimaryonly.
For more formation on the read concern levels, see Read Concern Levels.
For
"local"(default) or"majority"read concern level, you can specify theafterClusterTimeoption to have the read operation return data that meets the level requirement and the specified after cluster time requirement. For more information, see Read Operations and Causally Consistent Sessions.For more information on the read concern levels, see Read Concern Levels.
Behavior
Unless specified otherwise, the geoSearch command limits results to 50 documents.
Important
geoSearch is not supported for sharded clusters.
Examples
Consider the following example:
db.runCommand({
geoSearch : "places",
near: [ -73.9667, 40.78 ],
maxDistance : 6,
search : { type : "restaurant" },
limit : 30
})
The above command returns all documents with a type of restaurant having a maximum distance of 6 units from the coordinates [ -73.9667, 40.78 ] in the collection places up to a maximum of 30 results.
Override Default Read Concern
To override the default read concern level of "local", use the readConcern option.
The following operation on a replica set specifies a Read Concern of "majority" to read the most recent copy of the data confirmed as having been written to a majority of the nodes.
Note
To use read concern level of
"majority", replica sets must use WiredTiger storage engine and electionprotocol version 1.Starting in MongoDB 3.6, support for read concern
"majority"is enabled by default. For MongoDB 3.6.1 - 3.6.x, you can disable read concern"majority". For more information, see Disable Read Concern Majority.Regardless of the read concern level, the most recent data on a node may not reflect the most recent version of the data in the system.
db.runCommand(
{
geoSearch: "places",
near: [ -73.9667, 40.78 ],
search : { type : "restaurant" },
readConcern: { level: "majority" }
}
)
To ensure that a single thread can read its own writes, use "majority" read concern and "majority" write concern against the primary of the replica set.