Function MergeWorkerResults

pg_documentdb/src/commands/coll_stats.c:390–571

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

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

	ListCell *workerCell;

	result->totalSize = 0;
	result->storageSize = 0;
	int64 totalDocCount = 0;
	int64 totalDocCountFromStats = 0;
	int64 totalDocColumnSize = 0;
	int64 totalDocColumnSizeFromStats = 0;
	List *indexDocs = NIL;

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

		int64 workerTotalDocCount = 0;
		int64 workerTotalDocCountFromStats = 0;
		int32 averageDocSize = 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 */
				int64 value = BsonValueAsInt64(bson_iter_value(&workerIter));
				result->totalSize += value;
			}
			else if (strcmp(key, "total_tbl_size") == 0)
			{
				/* associative - sum up across nodes */
				int64 value = BsonValueAsInt64(bson_iter_value(&workerIter));
				result->storageSize += value;
			}
			else if (strcmp(key, "total_doc_count") == 0)
			{
				/*