MongoDB\Collection::count()

Definition

MongoDB\Collection::count()

Count the number of documents that match the filter criteria.

function count(
    array|object $filter = [],
    array $options = []
): integer

Parameters

$filter : array|object

The filter criteria that specifies the documents to count.

$options : array

An array specifying the desired options.

Name	Type	Description
collation	array|object	Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks. 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, the operation uses the collation specified for the collection. If no collation is specified for the collection or for the operation, MongoDB uses the simple binary comparison used in prior versions for string comparisons.
comment	mixed	Enables users to specify an arbitrary comment to help trace the operation through the database profiler, currentOp output, and logs. This option is available since MongoDB 4.4 and will result in an exception at execution time if specified for an older server version. New in version 1.13.
hint	string|array|object	The index to use. Specify either the index name as a string or the index key pattern as a document. If specified, then the query system will only consider plans using the hinted index. Changed in version 1.2: If a document is provided, it is passed to the command as-is. Previously, the library would convert the key pattern to an index name.
limit	integer	The maximum number of matching documents to return.
maxTimeMS	integer	The cumulative time limit in milliseconds for processing operations on the cursor. MongoDB aborts the operation at the earliest following interrupt point.
readConcern	MongoDB\Driver\ReadConcern	Read concern to use for the operation. Defaults to the collection's read concern. It is not possible to specify a read concern for individual operations as part of a transaction. Instead, set the readConcern option when starting the transaction.
readPreference	MongoDB\Driver\ReadPreference	Read preference to use for the operation. Defaults to the collection's read preference.
session	MongoDB\Driver\Session	Client session to associate with the operation. New in version 1.3.
skip	integer	The number of matching documents to skip before returning results.

Return Values

The number of documents matching the filter criteria.

Errors/Exceptions

MongoDB\Exception\UnexpectedValueException if the command response from the server was malformed.

MongoDB\Exception\UnsupportedException if options are used and not supported by the selected server (e.g. collation, readConcern, writeConcern).

MongoDB\Exception\InvalidArgumentException for errors related to the parsing of parameters or options.

MongoDB\Driver\Exception\RuntimeException for other errors at the extension level (e.g. connection errors).

Behavior

This method is deprecated and cannot be executed within a transaction. It has always been implemented using the count command. The behavior of the count command differs depending on the options passed to it and may or may not provide an accurate count. When no query filter is provided, the count command provides an estimate using collection metadata. Even when provided with a query filter the count command can return inaccurate results with a sharded cluster if orphaned documents exist or if a chunk migration is in progress. The MongoDB\Collection::countDocuments() method avoids these sharded cluster problems entirely.

When evaluating query criteria, MongoDB compares types and values according to its own comparison rules for BSON types, which differs from PHP's comparison and type juggling rules. When matching a special BSON type the query criteria should use the respective BSON class in the extension (e.g. use MongoDB\BSON\ObjectId to match an ObjectId).

See Also

• count command reference in the MongoDB manual

• MongoDB\Collection::countDocuments()

• MongoDB\Collection::estimatedDocumentCount()