MONGOC_COLLECT...DOCUMENT_COUNT(3) libmongoc MONGOC_COLLECT...DOCUMENT_COUNT(3) SYNOPSIS int64_t 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); PARAMETERS * collection: A mongoc_collection_t. * 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 con- tain 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 ex- ample code for mongoc_client_read_command_with_opts(). Read concern re- quires 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 col- lection, 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 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 command. The comment will appear in log messages, profiler output, and currentOp output. Requires MongoDB 4.4 or later. For a list of all options, see the MongoDB Manual entry on the count com- mand. DESCRIPTION This functions executes a count query on collection. In contrast with mongoc_collection_count_documents(), the count returned is not guaranteed to be accurate. This function is considered a retryable read operation. Upon a transient error (a network error, errors due to replica set failover, etc.) the oper- ation is safely retried once. If retryreads is false in the URI (see mongoc_uri_t) the retry behavior does not apply. Behavior This method is implemented using the count command. Due to an oversight in versions 5.0.0-5.0.8 of MongoDB, the count command was not included in ver- sion "1" of the Stable API. Applications using this method with the Stable API are recommended to upgrade their server version to 5.0.9+ or disable strict mode (via :symbol:`mongoc_server_api_strict()) to avoid encountering errors. 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 *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); } } SEE ALSO: mongoc_collection_count_documents() Count: Behavior in the MongoDB Manual AUTHOR MongoDB, Inc COPYRIGHT 2009-present, MongoDB, Inc. 1.30.8 Aug 27, 2026MONGOC_COLLECT...DOCUMENT_COUNT(3)
SYNOPSIS | PARAMETERS | DESCRIPTION | ERRORS | RETURNS | EXAMPLE | AUTHOR | COPYRIGHT
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