Function MergeWorkerResults

pg_documentdb/src/commands/db_stats.c:422–537

* Given a List of bsons that were dispatched by the query workers, * and a given collection & scale, merges the results into the target * DbStatsResult struct. */

 * DbStatsResult struct.
 */
static void
MergeWorkerResults(DbStatsResult *result,
				   List *workerResults, int32 scale)
{
	/* To merge the results, we apply each shard's results consecutively until we have everything
	 * each field is processed by its intent
	 */

	ListCell *workerCell;

	int64 totalDocCount = 0;
	int64 totalAllDocsSize = 0;
	int64 totalStorageSize = 0;
	int64 totalIndexSize = 0;
	int64 totalTotalSize = 0;

	foreach(workerCell, workerResults)
	{
		pgbson *workerBson = lfirst(workerCell);
		bson_iter_t workerIter;
		PgbsonInitIterator(workerBson, &workerIter);

		int64 workerDocCount = 0;
		int32 workerAvgDocSize = 0;
		int64 workerStorageSize = 0;
		int64 workerIndexSize = 0;
		int64 workerTotalSize = 0;

		int errorCode = 0;
		const char *errorMessage = NULL;

		while (bson_iter_next(&workerIter))
		{
			const char *key = bson_iter_key(&workerIter);
			if (strcmp(key, ErrCodeKey) == 0)
			{
				errorCode = BsonValueAsInt32(bson_iter_value(&workerIter));
			}
			else if (strcmp(key, ErrMsgKey) == 0)
			{
				const char *string = bson_iter_utf8(&workerIter, NULL);
				errorMessage = pstrdup(string);
			}
			else if (strcmp(key, "total_rel_size") == 0)
			{
				/* associative - sum up across nodes */
				workerTotalSize = BsonValueAsInt64(bson_iter_value(&workerIter));
			}
			else if (strcmp(key, "total_tbl_size") == 0)
			{
				/* associative - sum up across nodes */
				workerStorageSize = BsonValueAsInt64(bson_iter_value(&workerIter));
			}
			else if (strcmp(key, "total_doc_count") == 0)
			{
				/* associative - sum up across nodes */
				workerDocCount = BsonValueAsInt64(bson_iter_value(&workerIter));
			}