Provided by: libmongoc-doc_1.15.0-1_all bug


       mongoc_collection_estimated_document_count - mongoc_collection_estimated_document_count()


          mongoc_collection_estimated_document_count (mongoc_collection_t *collection,
                                                      const bson_t *opts,
                                                      const mongoc_read_prefs_t *read_prefs,
                                                      bson_t *reply,
                                                      bson_error_t *error);


       · collection: A mongoc_collection_t.

       · opts: A bson_t, NULL to ignore.

       · read_prefs: A mongoc_read_prefs_t or NULL.

       · reply:  A  location  for  an  uninitialized  bson_t  to store the command reply, NULL to
         ignore. If not NULL, reply will be initialized.

       · 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 Order, 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

       · skip: An int specifying how many documents matching the query should be  skipped  before

       · limit: An int specifying the maximum number of documents to count.


       This    functions   executes   a   count   query   on   collection.   In   contrast   with
       mongoc_collection_count_documents(), the count returned is not guaranteed to be accurate.


       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_count (mongoc_collection_t *collection, bson_t *query)
             bson_error_t error;
             int64_t count;
             bson_t* opts = BCON_NEW ("skip", BCON_INT64(5));

             count = mongoc_collection_estimated_document_count (
                collection, 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);




       MongoDB, Inc


       2017-present, MongoDB, Inc

1.15.0                                     Aug 13, 2MONGOC_COLLECTION_ESTIMATED_DOCUMENT_COUNT(3)