diff --git a/schema/mysql/schema.sql b/schema/mysql/schema.sql
index 5c834a74..2f9ea01d 100644
--- a/schema/mysql/schema.sql
+++ b/schema/mysql/schema.sql
@@ -573,8 +573,8 @@ CREATE TABLE downtime (
   id binary(20) NOT NULL COMMENT 'sha1(environment.name + name)',
   environment_id binary(20) NOT NULL COMMENT 'environment.id',
 
-  triggered_by_id binary(20) DEFAULT NULL COMMENT 'downtime.id',
-  parent_id binary(20) DEFAULT NULL COMMENT 'downtime.id',
+  triggered_by_id binary(20) DEFAULT NULL COMMENT 'The ID of the downtime that triggered this downtime. This is set when creating downtimes on a host or service higher up in the dependency chain using the "child_option" "DowntimeTriggeredChildren" and can also be set manually via the API.',
+  parent_id binary(20) DEFAULT NULL COMMENT 'For service downtimes, the ID of the host downtime that created this downtime by using the "all_services" flag of the schedule-downtime API.',
   object_type enum('host', 'service') NOT NULL,
   host_id binary(20) NOT NULL COMMENT 'host.id',
   service_id binary(20) DEFAULT NULL COMMENT 'service.id',
@@ -943,8 +943,8 @@ CREATE TABLE downtime_history (
   downtime_id binary(20) NOT NULL COMMENT 'downtime.id',
   environment_id binary(20) NOT NULL COMMENT 'environment.id',
   endpoint_id binary(20) DEFAULT NULL COMMENT 'endpoint.id',
-  triggered_by_id binary(20) DEFAULT NULL COMMENT 'downtime.id',
-  parent_id binary(20) DEFAULT NULL COMMENT 'downtime.id',
+  triggered_by_id binary(20) DEFAULT NULL COMMENT 'The ID of the downtime that triggered this downtime. This is set when creating downtimes on a host or service higher up in the dependency chain using the "child_option" "DowntimeTriggeredChildren" and can also be set manually via the API.',
+  parent_id binary(20) DEFAULT NULL COMMENT 'For service downtimes, the ID of the host downtime that created this downtime by using the "all_services" flag of the schedule-downtime API.',
   object_type enum('host', 'service') NOT NULL,
   host_id binary(20) NOT NULL COMMENT 'host.id',
   service_id binary(20) DEFAULT NULL COMMENT 'service.id',
diff --git a/schema/mysql/upgrades/1.0.0-rc2.sql b/schema/mysql/upgrades/1.0.0-rc2.sql
index be17a0d3..7f1bb6fa 100644
--- a/schema/mysql/upgrades/1.0.0-rc2.sql
+++ b/schema/mysql/upgrades/1.0.0-rc2.sql
@@ -16,8 +16,12 @@ UPDATE service_state SET properties_checksum = 0;
 ALTER TABLE service_state MODIFY COLUMN properties_checksum binary(20) COMMENT 'sha1(all properties)' NOT NULL;
 ALTER TABLE service_state ADD UNIQUE INDEX idx_service_state_service_id (service_id);
 
-ALTER TABLE downtime ADD COLUMN parent_id binary(20) AFTER triggered_by_id;
-ALTER TABLE downtime_history ADD COLUMN parent_id binary(20) AFTER triggered_by_id;
+ALTER TABLE downtime
+    ADD COLUMN parent_id binary(20) COMMENT 'For service downtimes, the ID of the host downtime that created this downtime by using the "all_services" flag of the schedule-downtime API.' AFTER triggered_by_id,
+    MODIFY COLUMN triggered_by_id binary(20) COMMENT 'The ID of the downtime that triggered this downtime. This is set when creating downtimes on a host or service higher up in the dependency chain using the "child_option" "DowntimeTriggeredChildren" and can also be set manually via the API.';
+ALTER TABLE downtime_history
+    ADD COLUMN parent_id binary(20) COMMENT 'For service downtimes, the ID of the host downtime that created this downtime by using the "all_services" flag of the schedule-downtime API.' AFTER triggered_by_id,
+    MODIFY COLUMN triggered_by_id binary(20) COMMENT 'The ID of the downtime that triggered this downtime. This is set when creating downtimes on a host or service higher up in the dependency chain using the "child_option" "DowntimeTriggeredChildren" and can also be set manually via the API.';
 
 ALTER TABLE checkcommand_argument MODIFY COLUMN argument_order smallint DEFAULT NULL;
 ALTER TABLE eventcommand_argument MODIFY COLUMN argument_order smallint DEFAULT NULL;