Function command_list_databases

pg_documentdb/src/commands/db_stats.c:139–230

Datum
command_list_databases(PG_FUNCTION_ARGS)
{
	ReportFeatureUsage(FEATURE_COMMAND_LIST_DATABASES);

	pgbson *spec = PG_GETARG_PGBSON(0);

	bool nameOnly = false;
	pgbson *filter = NULL;

	bson_iter_t specIter;
	PgbsonInitIterator(spec, &specIter);
	while (bson_iter_next(&specIter))
	{
		const char *key = bson_iter_key(&specIter);
		if (strcmp(key, "nameOnly") == 0)
		{
			EnsureTopLevelFieldIsBooleanLike("nameOnly", &specIter);
			nameOnly = BsonValueAsBool(bson_iter_value(&specIter));
		}
		else if (strcmp(key, "filter") == 0)
		{
			EnsureTopLevelFieldType("filter", &specIter, BSON_TYPE_DOCUMENT);
			filter = PgbsonInitFromDocumentBsonValue(bson_iter_value(&specIter));
		}
		else if (strcmp(key, "listDatabases") == 0)
		{
			/* ignore */
		}
		else if (!IsCommonSpecIgnoredField(key))
		{
			ereport(ERROR, (errcode(ERRCODE_DOCUMENTDB_BADVALUE),
							errmsg("%s is an unrecognized field name", key)));
		}
	}

	const char *sizeOnDiskSelector = "";
	const char *totalSizeSelector = "";
	const char *filterString = "";

	if (!nameOnly)
	{
		sizeOnDiskSelector = ", 0::int8 AS \"sizeOnDisk\", false AS empty";
		totalSizeSelector =
			"pg_catalog.pg_database_size(pg_catalog.current_database())::int8 AS \"totalSize\", ";
	}

	if (filter != NULL)
	{
		filterString = FormatSqlQuery("WHERE document OPERATOR(%s.@@) $1",
									  ApiCatalogSchemaName);
	}

	/* We can definitely do better here. TODO: Improve size tracking etc. */
	const char *cmdStr = FormatSqlQuery(
		"WITH r1 AS (SELECT DISTINCT database_name AS name %s FROM %s.collections),"
		"r2 AS (SELECT %s.row_get_bson(r1) AS document FROM r1),"
		"r3 AS (SELECT document FROM r2 %s),"