The commitQuorum option to the createIndexes command is only supported in MongoDB 4.4+ servers, but it is not validated in the command functions. Do not pass commitQuorum if connected to server versions less than 4.4. Using the commitQuorum option on server versions less than 4.4 may have adverse effects on index builds.

/* gcc example-create-indexes.c -o example-create-indexes $(pkg-config --cflags


 * --libs libmongoc-1.0) */
/* ./example-create-indexes [CONNECTION_STRING [COLLECTION_NAME]] */
#include <mongoc/mongoc.h>
#include <stdio.h>
#include <stdlib.h>
int
main (int argc, char *argv[])
{


   mongoc_client_t *client;


   const char *uri_string =


      "mongodb://127.0.0.1/?appname=create-indexes-example";


   mongoc_uri_t *uri;


   mongoc_database_t *db;


   const char *collection_name = "test";


   bson_t keys;


   char *index_name;


   bson_t *create_indexes;


   bson_t reply;


   char *reply_str;


   bson_error_t error;


   bool r;


   mongoc_init ();


   if (argc > 1) {


      uri_string = argv[1];


   }


   if (argc > 2) {


      collection_name = argv[2];


   }


   uri = mongoc_uri_new_with_error (uri_string, &error);


   if (!uri) {


      fprintf (stderr,


               "failed to parse URI: %s\n"


               "error message:       %s\n",


               uri_string,


               error.message);


      return EXIT_FAILURE;


   }


   client = mongoc_client_new_from_uri (uri);


   if (!client) {


      return EXIT_FAILURE;


   }


   mongoc_client_set_error_api (client, 2);


   db = mongoc_client_get_database (client, "test");


   /* ascending index on field "x" */


   bson_init (&keys);


   BSON_APPEND_INT32 (&keys, "x", 1);


   index_name = mongoc_collection_keys_to_index_string (&keys);


   create_indexes = BCON_NEW ("createIndexes",


                              BCON_UTF8 (collection_name),


                              "indexes",


                              "[",


                              "{",


                              "key",


                              BCON_DOCUMENT (&keys),


                              "name",


                              BCON_UTF8 (index_name),


                              "}",


                              "]");


   r = mongoc_database_write_command_with_opts (


      db, create_indexes, NULL /* opts */, &reply, &error);


   reply_str = bson_as_json (&reply, NULL);


   printf ("%s\n", reply_str);


   if (!r) {


      fprintf (stderr, "Error in createIndexes: %s\n", error.message);


   }


   bson_free (index_name);


   bson_free (reply_str);


   bson_destroy (&reply);


   bson_destroy (create_indexes);


   mongoc_database_destroy (db);


   mongoc_uri_destroy (uri);


   mongoc_client_destroy (client);


   mongoc_cleanup ();


   return r ? EXIT_SUCCESS : EXIT_FAILURE;
}