ds mongo OPTIMIZE speed up queries with indices

src/plugins/ds_mongo.c

@@ -2978,8 +2978,9 @@ srpds_mongo_install(const struct lys_module *mod, sr_datastore_t ds, const char
     mongo_plg_conn_data_t *pdata = (mongo_plg_conn_data_t *)plg_data;
     sr_error_info_t *err_info = NULL;
     bson_error_t error;
-    bson_t *bson_query = NULL, *bson_index_key1 = NULL;
-    mongoc_index_model_t *im = NULL;
+    uint32_t i, idx_cnt = 3;
+    bson_t *bson_query = NULL, *bson_index_keys[idx_cnt];
+    mongoc_index_model_t *im[idx_cnt];
     char *process_user = NULL, *process_group = NULL;
     struct timespec spec = {0};
 
@@ -2989,10 +2990,16 @@ srpds_mongo_install(const struct lys_module *mod, sr_datastore_t ds, const char
         goto cleanup;
     }
 
-    /* create indices on prev for quicker data retrieval while managing the userordered lists */
-    bson_index_key1 = BCON_NEW("prev", BCON_INT32(1));
-    im = mongoc_index_model_new(bson_index_key1, NULL /* opts */);
-    if (!mongoc_collection_create_indexes_with_opts(mdata.module, &im, 1, NULL /* opts */, NULL /* reply */, &error)) {
+    /* create a compound index on prev and path for load_next(),
+     * compound index on order and path_no_pred for srpds_shift_uo_list_recursively()
+     * and index on path_modif for quicker loading */
+    bson_index_keys[0] = BCON_NEW("prev", BCON_INT32(1), "path_no_pred", BCON_INT32(1));
+    bson_index_keys[1] = BCON_NEW("order", BCON_INT32(1), "path_no_pred", BCON_INT32(1));
+    bson_index_keys[2] = BCON_NEW("path_modif", BCON_INT32(1));
+    for (i = 0; i < idx_cnt; ++i) {
+        im[i] = mongoc_index_model_new(bson_index_keys[i], NULL /* opts */);
+    }
+    if (!mongoc_collection_create_indexes_with_opts(mdata.module, im, idx_cnt, NULL /* opts */, NULL /* reply */, &error)) {
         ERRINFO(&err_info, plugin_name, SR_ERR_OPERATION_FAILED, "mongoc_collection_create_indexes_with_opts", error.message)
         goto cleanup;
     }
@@ -3038,8 +3045,10 @@ srpds_mongo_install(const struct lys_module *mod, sr_datastore_t ds, const char
 cleanup:
     free(process_user);
     free(process_group);
-    mongoc_index_model_destroy(im);
-    bson_destroy(bson_index_key1);
+    for (i = 0; i < idx_cnt; ++i) {
+        mongoc_index_model_destroy(im[i]);
+        bson_destroy(bson_index_keys[i]);
+    }
     bson_destroy(bson_query);
     srpds_data_destroy(pdata, &mdata);
     return err_info;