mongoc_collection_count - Man Page



This function is deprecated and should not be used in new code. Use mongoc_collection_count_documents or mongoc_collection_estimated_document_count instead.

mongoc_collection_count_documents has similar performance to calling mongoc_collection_count with a non-NULL query, and is guaranteed to retrieve an accurate collection count. See migrating from deprecated count functions for details.

mongoc_collection_estimated_document_count has the same performance as calling mongoc_collection_count with a NULL query, but is not guaranteed to retrieve an accurate collection count.

This function is considered a retryable read operation. Upon a transient 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.


mongoc_collection_count (mongoc_collection_t *collection,
                         mongoc_query_flags_t flags,
                         const bson_t *query,
                         int64_t skip,
                         int64_t limit,
                         const mongoc_read_prefs_t *read_prefs,
                         bson_error_t *error)
 BSON_GNUC_DEPRECATED_FOR (mongoc_collection_count_documents or



This function shall execute a count query on the underlying 'collection'. The bson 'query' is not validated, simply passed along as appropriate to the server.  As such, compatibility and errors should be validated in the appropriate server documentation.

For more information, see the query reference at the MongoDB website.

The mongoc_read_concern_t specified on the mongoc_collection_t will be used, if any. If read_prefs is NULL, the collection's read preferences are used.


Errors are propagated via the error parameter.


-1 on failure, otherwise the number of documents counted.


#include <bson/bson.h>
#include <mongoc/mongoc.h>
#include <stdio.h>

static void
print_query_count (mongoc_collection_t *collection, bson_t *query)
   bson_error_t error;
   int64_t count;

   count = mongoc_collection_count (
      collection, MONGOC_QUERY_NONE, query, 0, 0, NULL, &error);

   if (count < 0) {
      fprintf (stderr, "Count failed: %s\n", error.message);
   } else {
      printf ("%" PRId64 " documents counted.\n", count);


MongoDB, Inc


Apr 09, 2021 1.17.5 libmongoc