Creating Indexes¶
To create indexes on a MongoDB collection, execute the createIndexes command
with a command function like mongoc_database_write_command_with_opts() or
mongoc_collection_write_command_with_opts(). See the MongoDB
Manual entry for the createIndexes command for details.
Warning
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.
Example¶
example-create-indexes.c¶
/* 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;
}