7 files changed, 22 insertions, 9 deletions
diff --git a/include/fieldstat/fieldstat.h b/include/fieldstat/fieldstat.h
index d184bc4..0e48098 100644
--- a/include/fieldstat/fieldstat.h
+++ b/include/fieldstat/fieldstat.h
@@ -222,9 +222,9 @@ struct fieldstat_tag_list *fieldstat_get_shared_tags(const struct fieldstat *ins
 int fieldstat_find_cube(const struct fieldstat *instance, const struct fieldstat_tag *shared_tags, size_t n_shared_tags);
 
 /* 
-    get the parameter max_n_cell of fieldstat_create_cube. -1 is a valid value, meaning cube has no metric. Return FS_ERR_INVALID_CUBE_ID if cube_id is invalid.
+    get the cell numbers in a cube. Return FS_ERR_INVALID_CUBE_ID if cube_id is invalid.
 */
-int fieldstat_get_max_cell_id(const struct fieldstat *instance, int cube_id);
+int fieldstat_get_used_sampling(const struct fieldstat *instance, int cube_id);
 
 /*
     * @brief Get the value of a metric of a cell.
diff --git a/src/exporter/cjson_exporter.c b/src/exporter/cjson_exporter.c
index f9456d1..4055182 100644
--- a/src/exporter/cjson_exporter.c
+++ b/src/exporter/cjson_exporter.c
@@ -668,7 +668,7 @@ struct cellwise_rec_for_export *read_tag_and_field(const struct fieldstat *insta
 
     size_t n_cell_total = 0;
     for (int i = 0; i < cube_id_len; i++) {
-        n_cell_total += fieldstat_get_max_cell_id(instance, cube_id[i]);
+        n_cell_total += fieldstat_get_used_sampling(instance, cube_id[i]);
     }
     free(cube_id);
     if (n_cell_total == 0) {
diff --git a/src/fieldstat.c b/src/fieldstat.c
index 0f3cffc..e086ffd 100644
--- a/src/fieldstat.c
+++ b/src/fieldstat.c
@@ -1032,7 +1032,7 @@ int fieldstat_get_metrics_used_by_cube(const struct fieldstat *instance, int cub
 
     int all_available_metric_count = 0;
     if (cube->valid_metric_arr_len == 0) {
-        return 0;
+        return FS_OK;
     }
     int *tmp_ids = (int *)malloc(sizeof(int) * cube->valid_metric_arr_len);
     for (int i = 0; i < cube->valid_metric_arr_len; i++) {
@@ -1045,7 +1045,7 @@ int fieldstat_get_metrics_used_by_cube(const struct fieldstat *instance, int cub
     }
     if (all_available_metric_count == 0) {
         free(tmp_ids);
-        return 0;
+        return FS_OK;
     }
 
     *metric_id_out = tmp_ids;
@@ -1355,16 +1355,14 @@ void fieldstat_get_cells_used_by_cube(const struct fieldstat *instance, int cube
     *n_cell = n_cell_ret;
 }
 
-int fieldstat_get_max_cell_id(const struct fieldstat *instance, int cube_id)
+int fieldstat_get_used_sampling(const struct fieldstat *instance, int cube_id)
 {
     const struct fs_cube *cube = instance->cube[cube_id];
     if (cube == NULL) {
         return FS_ERR_INVALID_CUBE_ID;
     }
 
-    int max_id;
-    (void)cell_manager_dump(cube->cell_manager, &max_id);
-    return max_id;
+    return cell_manager_get_cardinality(cube->cell_manager);
 }
 
 int fieldstat_find_cube(const struct fieldstat *instance, const struct fieldstat_tag *shared_tags, size_t n_shared_tags)
diff --git a/src/tags/cell_manager.c b/src/tags/cell_manager.c
index a77ca3f..f4b767e 100644
--- a/src/tags/cell_manager.c
+++ b/src/tags/cell_manager.c
@@ -433,6 +433,15 @@ void cell_manager_merge_topk(struct cell_manager *dest, const struct cell_manage
     heavy_keeper_result_free(result);
 }
 
+int cell_manager_get_cardinality(const struct cell_manager *pthis)
+{
+    if (pthis->sampling_mode == SAMPLING_MODE_COMPREHENSIVE) {
+        return pthis->current_cell_num;
+    } else {
+        return heavy_keeper_get_cardinality(pthis->topk_tag_id_map);
+    }
+}
+
 void cube_manager_free(struct cube_manager *pthis)
 {
     tag_id_map_free(pthis->head);
diff --git a/src/tags/cell_manager.h b/src/tags/cell_manager.h
index 3c85abb..b85177c 100644
--- a/src/tags/cell_manager.h
+++ b/src/tags/cell_manager.h
@@ -17,6 +17,7 @@ const struct tag_hash_key *cell_manager_get_tag_by_cell_id(const struct cell_man
 long long cell_manager_get_count_by_tag(const struct cell_manager *pthis, const struct tag_hash_key *tag);
 const struct tag_hash_key **cell_manager_dump(const struct cell_manager *pthis, int *array_len);
 int cell_manager_find(const struct cell_manager *pthis, const struct tag_hash_key *tag);
+int cell_manager_get_cardinality(const struct cell_manager *pthis);
 
 int cell_manager_add_cell(struct cell_manager *pthis, const struct tag_hash_key *tag);
 int cell_manager_add_cell_topk(struct cell_manager *pthis, const struct tag_hash_key *tag, unsigned int count, int *popped_cell_id);
diff --git a/src/tags/heavy_keeper.c b/src/tags/heavy_keeper.c
index f79c479..39bb4cf 100644
--- a/src/tags/heavy_keeper.c
+++ b/src/tags/heavy_keeper.c
@@ -276,6 +276,10 @@ struct heavy_keeper_result *heavy_keeper_query(const struct heavy_keeper *hk) {
     return stats;
 }
 
+size_t heavy_keeper_get_cardinality(const struct heavy_keeper *hk) {
+    return sorted_set_cardinality(hk->top_K_heap);
+}
+
 int heavy_keeper_query_one(const struct heavy_keeper *hk, const struct tag_hash_key *tag, unsigned int *count_out, int *cell_id_out)
 {
     if (count_out != NULL) {
diff --git a/src/tags/heavy_keeper.h b/src/tags/heavy_keeper.h
index 5d240c2..216d8f6 100644
--- a/src/tags/heavy_keeper.h
+++ b/src/tags/heavy_keeper.h
@@ -63,6 +63,7 @@ struct heavy_keeper_result *heavy_keeper_query(const struct heavy_keeper *hk);
 
 int heavy_keeper_query_one(const struct heavy_keeper *hk, const struct tag_hash_key *tag, unsigned int *count_out, int *cube_id_out);
 
+size_t heavy_keeper_get_cardinality(const struct heavy_keeper *hk);
 /**
  * @brief   free a heavy keeper query result.
  * @param   stats_hd     the pointer to the heavy keeper query result.