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Query Modifiers¶
Introduction¶
In addition to the MongoDB Query Operators, there are a number of “meta” operators that let you modify the output or behavior of a query. On the server, MongoDB treats the query and the options as a single object. The mongo shell and driver interfaces may provide cursor methods that wrap these options. When possible, use these methods; otherwise, you can add these options using either of the following syntax:
db.collection.find( { <query> } )._addSpecial( <option> )
db.collection.find( { $query: { <query> }, <option> } )
Operators¶
Modifiers¶
Many of these operators have corresponding methods in the shell. These methods provide a straightforward and user-friendly interface and are the preferred way to add these options.
Name | Description |
---|---|
$comment | Adds a comment to the query to identify queries in the database profiler output. |
$explain | Forces MongoDB to report on query execution plans. See explain(). |
$hint | Forces MongoDB to use a specific index. See hint() |
$maxScan | Limits the number of documents scanned. |
$maxTimeMS | Specifies a cumulative time limit in milliseconds for processing operations on a cursor. See maxTimeMS(). |
$max | Specifies an exclusive upper limit for the index to use in a query. See max(). |
$min | Specifies an inclusive lower limit for the index to use in a query. See min(). |
$orderby | Returns a cursor with documents sorted according to a sort specification. See sort(). |
$returnKey | Forces the cursor to only return fields included in the index. |
$showDiskLoc | Modifies the documents returned to include references to the on-disk location of each document. |
$snapshot | Forces the query to use the index on the _id field. See snapshot(). |
$query | Wraps a query document. |