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MONGOC_COLLEC...OUNT_DOCUMENTS(3) libmongoc MONGOC_COLLEC...OUNT_DOCUMENTS(3) SYNOPSIS int64_t mongoc_collection_count_documents (mongoc_collection_t *collection, const bson_t *filter, const bson_t *opts, const mongoc_read_prefs_t *read_prefs, bson_t *reply, bson_error_t *error); PARAMETERS • collection: A mongoc_collection_t. • filter: A bson_t containing the filter. • opts: A bson_t, NULL to ignore. • read_prefs: A mongoc_read_prefs_t or NULL. • reply: A maybe-NULL pointer to overwritable storage for a bson_t to contain the results. • error: An optional location for a bson_error_t or NULL. opts may be NULL or a BSON document with additional command options: • readConcern: Construct a mongoc_read_concern_t and use mongoc_read_concern_append() to add the read concern to opts. See the example code for mongoc_client_read_command_with_opts(). Read concern requires MongoDB 3.2 or later, otherwise an error is returned. • sessionId: First, construct a mongoc_client_session_t with mongoc_client_start_session(). You can begin a transaction with mongoc_client_session_start_transaction(), optionally with a mongoc_transaction_opt_t that overrides the options inherited from collection, and use mongoc_client_session_append() to add the session to opts. See the example code for mongoc_client_session_t. • collation: Configure textual comparisons. See Setting Collation Or- der, and the MongoDB Manual entry on Collation. Collation requires MongoDB 3.2 or later, otherwise an error is returned. • serverId: To target a specific server, include an int32 "serverId" field. Obtain the id by calling mongoc_client_select_server(), then mongoc_server_description_id() on its return value. • skip: An int specifying how many documents matching the query should be skipped before counting. • limit: An int specifying the maximum number of documents to count. • comment: A bson_value_t specifying the comment to attach to this com- mand. The comment will appear in log messages, profiler output, and currentOp output. Only string values are supported prior to MongoDB 4.4. • hint: A document or string that specifies the index to use to support the query predicate. Other options are included in the sent aggregate command. For a list of all options, see the MongoDB Manual entry on the aggregate command. DESCRIPTION This functions executes a count query on collection. In contrast with mongoc_collection_estimated_document_count(), the count returned is guaranteed to be accurate. This function is considered a retryable read operation. Upon a tran- sient error (a network error, errors due to replica set failover, etc.) the operation is safely retried once. If retryreads is false in the URI (see mongoc_uri_t) the retry behavior does not apply. ERRORS Errors are propagated via the error parameter. RETURNS -1 on failure, otherwise the number of documents counted. EXAMPLE #include <bson/bson.h> #include <mongoc/mongoc.h> #include <stdio.h> static void print_count (mongoc_collection_t *collection, bson_t *filter) { bson_error_t error; int64_t count; bson_t* opts = BCON_NEW ("skip", BCON_INT64(5)); count = mongoc_collection_count_documents ( collection, filter, opts, NULL, NULL, &error); bson_destroy (opts); if (count < 0) { fprintf (stderr, "Count failed: %s\n", error.message); } else { printf ("%" PRId64 " documents counted.\n", count); } } MIGRATING FROM DEPRECATED COUNT FUNCTIONS When migrating to mongoc_collection_count_documents() from the depre- cated mongoc_collection_count() or mongoc_collection_count_with_opts(), the following query operators in the filter must be replaced: +-------------+----------------------------+ | Operator | Replacement | +-------------+----------------------------+ | $where | $expr | +-------------+----------------------------+ | $near | $geoWithin with $center | +-------------+----------------------------+ | $nearSphere | $geoWithin with | | | $centerSphere | +-------------+----------------------------+ $expr requires MongoDB 3.6+ SEE ALSO: mongoc_collection_estimated_document_count() AUTHOR MongoDB, Inc COPYRIGHT 2009-present, MongoDB, Inc. 1.30.2 Apr 12, 2025MONGOC_COLLEC...OUNT_DOCUMENTS(3)
SYNOPSIS | PARAMETERS | DESCRIPTION | ERRORS | RETURNS | EXAMPLE | MIGRATING FROM DEPRECATED COUNT FUNCTIONS | AUTHOR | COPYRIGHT
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