Optional. The projection specification to determine which fields to include in the returned documents. See Project Fields to Return from Query and Projection Operators.

find() operations on views do not support the following projection operators:

• $
• $elemMatch
• $slice
• $meta

Optional. The number of documents to return in the first batch. Defaults to 101. A batchSize of 0 means that the cursor will be established, but no documents will be returned in the first batch.

Unlike the previous wire protocol version, a batchSize of 1 for the find command does not close the cursor.

Optional. The cumulative time limit in milliseconds for processing operations on the cursor. MongoDB aborts the operation at the earliest following interrupt point.

Optional. Specifies the read concern.

The readConcern option has the following syntax:

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 the primary only.

For more formation on the read concern levels, see Read Concern Levels.

For "local" (default) or "majority" read concern level, you can specify the afterClusterTime option 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.

The getMore command uses the readConcern level specified in the originating find command.

Optional. An internal command for replaying a replica set’s oplog.

To use oplogReplay, the find field must refer to a capped collection and you must provide a filter option comparing the ts document field to a timestamp using one of the following comparison operators:

• $gte
• $gt
• $eq

For example, the following command replays documents from the data capped collection with a timestamp later than or equal to January 1st, 2018 UTC:

{ find: "data",
  oplogReplay: true,
  filter: { ts: { $gte: new Timestamp(1514764800, 0) } } }

Optional. For queries against a sharded collection, allows the command (or subsequent getMore commands) to return partial results, rather than an error, if one or more queried shards are unavailable.

Optional.

Specifies the collation to use for the operation.

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

The collation option has the following syntax:

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

When specifying collation, the locale field is mandatory; all other collation fields are optional. For descriptions of the fields, see Collation Document.

If the collation is unspecified but the collection has a default collation (see db.createCollection()), the operation uses the collation specified for the collection.

If no collation is specified for the collection or for the operations, MongoDB uses the simple binary comparison used in prior versions for string comparisons.

You cannot specify multiple collations for an operation. For example, you cannot specify different collations per field, or if performing a find with a sort, you cannot use one collation for the find and another for the sort.