diff --git a/configobject/history/history.go b/configobject/history/history.go
index a1ba3af4..b59d054a 100644
--- a/configobject/history/history.go
+++ b/configobject/history/history.go
@@ -391,9 +391,15 @@ func commentHistoryWorker(super *supervisor.Supervisor) {
 
 func flappingHistoryWorker(super *supervisor.Supervisor) {
 	statements := []string{
-		`REPLACE INTO flapping_history (id, environment_id, endpoint_id, object_type, host_id, service_id, event_time,` +
+		`INSERT INTO flapping_history (id, environment_id, endpoint_id, object_type, host_id, service_id, start_time, end_time, ` +
 			`percent_state_change, flapping_threshold_low, flapping_threshold_high)` +
-			`VALUES (?,?,?,?,?,?,?,?,?,?)`,
+			`VALUES (?,?,?,?,?,?,?,?,?,?,?)` +
+			`ON DUPLICATE KEY UPDATE ` +
+			`start_time=IFNULL(NULLIF(start_time, 0), VALUES(start_time)),` +
+			`end_time=IFNULL(NULLIF(end_time, 0), VALUES(end_time)),` +
+			`percent_state_change=IFNULL(NULLIF(percent_state_change, 0), VALUES(percent_state_change)),` +
+			`flapping_threshold_low=IFNULL(NULLIF(flapping_threshold_low, 0), VALUES(flapping_threshold_low)),` +
+			`flapping_threshold_high=IFNULL(NULLIF(flapping_threshold_high, 0), VALUES(flapping_threshold_high))`,
 		`REPLACE INTO history (id, environment_id, endpoint_id, object_type, host_id, service_id, notification_history_id,` +
 			`state_history_id, downtime_history_id, comment_history_id, flapping_history_id, event_type, event_time)` +
 			`VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?)`,
@@ -401,15 +407,15 @@ func flappingHistoryWorker(super *supervisor.Supervisor) {
 
 	dataFunctions := []func(values map[string]interface{}) []interface{}{
 		func(values map[string]interface{}) []interface{} {
-			id := uuid.MustParse(values["id"].(string))
 			data := []interface{}{
-				id[:],
+				utils.EncodeChecksum(values["id"].(string)),
 				super.EnvId,
 				utils.DecodeHexIfNotNil(values["endpoint_id"]),
 				values["object_type"].(string),
 				utils.EncodeChecksum(values["host_id"].(string)),
 				utils.DecodeHexIfNotNil(values["service_id"]),
-				values["event_time"],
+				values["start_time"],
+				values["end_time"],
 				values["percent_state_change"],
 				values["flapping_threshold_low"],
 				values["flapping_threshold_high"],
@@ -419,7 +425,6 @@ func flappingHistoryWorker(super *supervisor.Supervisor) {
 		},
 		func(values map[string]interface{}) []interface{} {
 			eventId := uuid.MustParse(values["event_id"].(string))
-			flappingHistoryId := uuid.MustParse(values["id"].(string))
 
 			var eventTime string
 			switch values["event_type"] {
@@ -440,7 +445,7 @@ func flappingHistoryWorker(super *supervisor.Supervisor) {
 				nil,
 				nil,
 				nil,
-				flappingHistoryId[:],
+				utils.EncodeChecksum(values["id"].(string)),
 				values["event_type"],
 				eventTime,
 			}
@@ -454,9 +459,18 @@ func flappingHistoryWorker(super *supervisor.Supervisor) {
 
 func acknowledgementHistoryWorker(super *supervisor.Supervisor) {
 	statements := []string{
-		`REPLACE INTO acknowledgement_history (id, environment_id, endpoint_id, object_type, host_id, service_id, event_time,` +
-			`author, comment, expire_time, is_sticky, is_persistent)` +
-			`VALUES (?,?,?,?,?,?,?,?,?,?,?,?)`,
+		`INSERT INTO acknowledgement_history (id, environment_id, endpoint_id, object_type, host_id, service_id, set_time, clear_time,` +
+			`author, cleared_by, comment, expire_time, is_sticky, is_persistent)` +
+			`VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?)` +
+			`ON DUPLICATE KEY UPDATE ` +
+			`set_time=IFNULL(NULLIF(set_time, 0), VALUES(set_time)),` +
+			`clear_time=IFNULL(NULLIF(clear_time, 0), VALUES(clear_time)),` +
+			`author=IFNULL(NULLIF(author, ''), VALUES(author)),` +
+			`cleared_by=IFNULL(NULLIF(cleared_by, ''), VALUES(cleared_by)),` +
+			`comment=IFNULL(NULLIF(comment, ''), VALUES(comment)),` +
+			`expire_time=IFNULL(NULLIF(expire_time, 0), VALUES(expire_time)),` +
+			`is_sticky=IFNULL(NULLIF(is_sticky, 'n'), VALUES(is_sticky)),` +
+			`is_persistent=IFNULL(NULLIF(is_persistent, 'n'), VALUES(is_persistent))`,
 		`REPLACE INTO history (id, environment_id, endpoint_id, object_type, host_id, service_id,` +
 			` acknowledgement_history_id, event_type, event_time)` +
 			`VALUES (?,?,?,?,?,?,?,?,?)`,
@@ -464,17 +478,18 @@ func acknowledgementHistoryWorker(super *supervisor.Supervisor) {
 
 	dataFunctions := []func(values map[string]interface{}) []interface{}{
 		func(values map[string]interface{}) []interface{} {
-			id := uuid.MustParse(values["id"].(string))
 			data := []interface{}{
-				id[:],
+				utils.EncodeChecksum(values["id"].(string)),
 				super.EnvId,
 				utils.DecodeHexIfNotNil(values["endpoint_id"]),
 				values["object_type"].(string),
 				utils.EncodeChecksum(values["host_id"].(string)),
 				utils.DecodeHexIfNotNil(values["service_id"]),
-				values["event_time"],
-				values["author"],
-				values["comment"],
+				values["set_time"],
+				values["clear_time"],
+				utils.DefaultIfNil(values["author"], ""),
+				values["cleared_by"],
+				utils.DefaultIfNil(values["comment"], ""),
 				values["expire_time"],
 				utils.RedisIntToDBBoolean(values["is_sticky"]),
 				utils.RedisIntToDBBoolean(values["is_persistent"]),
@@ -483,18 +498,26 @@ func acknowledgementHistoryWorker(super *supervisor.Supervisor) {
 			return data
 		},
 		func(values map[string]interface{}) []interface{} {
-			id := uuid.MustParse(values["id"].(string))
+			eventId := uuid.MustParse(values["event_id"].(string))
+
+			var eventTime string
+			switch values["event_type"] {
+			case "ack_set":
+				eventTime = values["set_time"].(string)
+			case "ack_clear":
+				eventTime = values["clear_time"].(string)
+			}
 
 			data := []interface{}{
-				id[:],
+				eventId[:],
 				super.EnvId,
 				utils.DecodeHexIfNotNil(values["endpoint_id"]),
 				values["object_type"].(string),
 				utils.EncodeChecksum(values["host_id"].(string)),
 				utils.DecodeHexIfNotNil(values["service_id"]),
-				id[:],
+				utils.EncodeChecksum(values["id"].(string)),
 				values["event_type"],
-				values["event_time"],
+				eventTime,
 			}
 
 			return data
diff --git a/etc/schema/mysql/mysql.schema.sql b/etc/schema/mysql/mysql.schema.sql
index 4345133e..d4e93489 100644
--- a/etc/schema/mysql/mysql.schema.sql
+++ b/etc/schema/mysql/mysql.schema.sql
@@ -912,14 +912,15 @@ CREATE TABLE comment_history (
 ) ENGINE=InnoDb ROW_FORMAT=DYNAMIC DEFAULT CHARSET=utf8mb4 COLLATE utf8mb4_bin;
 
 CREATE TABLE flapping_history (
-  id binary(16) NOT NULL COMMENT 'UUID',
+  id binary(20) NOT NULL COMMENT 'sha1(environment.name + "host"|"service" + host|service.name + start_time)',
   environment_id binary(20) NOT NULL COMMENT 'environment.id',
   endpoint_id binary(20) NULL DEFAULT NULL COMMENT 'endpoint.id',
   object_type enum('host', 'service') NOT NULL,
   host_id binary(20) NOT NULL COMMENT 'host.id',
   service_id binary(20) NULL DEFAULT NULL COMMENT 'service.id',
 
-  event_time bigint(20) unsigned NOT NULL,
+  start_time bigint(20) unsigned NOT NULL,
+  end_time bigint(20) unsigned NULL DEFAULT NULL,
   percent_state_change float unsigned NOT NULL,
   flapping_threshold_low float unsigned NOT NULL,
   flapping_threshold_high float unsigned NOT NULL,
@@ -928,25 +929,27 @@ CREATE TABLE flapping_history (
 ) ENGINE=InnoDb ROW_FORMAT=DYNAMIC DEFAULT CHARSET=utf8mb4 COLLATE utf8mb4_bin;
 
 CREATE TABLE acknowledgement_history (
-  id binary(16) NOT NULL COMMENT 'UUID',
+  id binary(20) NOT NULL COMMENT 'sha1(environment.name + "host"|"service" + host|service.name + set_time)',
   environment_id binary(20) NOT NULL COMMENT 'environment.id',
   endpoint_id binary(20) NULL DEFAULT NULL COMMENT 'endpoint.id',
   object_type enum('host', 'service') NOT NULL,
   host_id binary(20) NOT NULL COMMENT 'host.id',
   service_id binary(20) NULL DEFAULT NULL COMMENT 'service.id',
 
-  event_time bigint(20) unsigned NOT NULL,
+  set_time bigint(20) unsigned NOT NULL,
+  clear_time bigint(20) unsigned NULL DEFAULT NULL,
   author varchar(255) NOT NULL COLLATE utf8mb4_unicode_ci,
+  cleared_by varchar(255) DEFAULT NULL COLLATE utf8mb4_unicode_ci,
   comment text DEFAULT NULL,
   expire_time bigint(20) unsigned DEFAULT NULL,
-  is_sticky enum('y','n') DEFAULT NULL,
-  is_persistent enum('y','n') DEFAULT NULL,
+  is_sticky enum('y','n') NOT NULL,
+  is_persistent enum('y','n') NOT NULL,
 
   PRIMARY KEY (id)
 ) ENGINE=InnoDb ROW_FORMAT=DYNAMIC DEFAULT CHARSET=utf8mb4 COLLATE utf8mb4_bin;
 
 CREATE TABLE history (
-  id binary(16) NOT NULL COMMENT 'notification_history_id, state_history_id, flapping_history_id, acknowledgement_history_id or UUID',
+  id binary(16) NOT NULL COMMENT 'notification_history_id, state_history_id or UUID',
   environment_id binary(20) NOT NULL COMMENT 'environment.id',
   endpoint_id binary(20) NULL DEFAULT NULL COMMENT 'endpoint.id',
   object_type enum('host', 'service') NOT NULL,
@@ -956,8 +959,8 @@ CREATE TABLE history (
   state_history_id binary(16) NULL DEFAULT NULL COMMENT 'state_history.id',
   downtime_history_id binary(20) NULL DEFAULT NULL COMMENT 'downtime_history.downtime_id',
   comment_history_id binary(20) NULL DEFAULT NULL COMMENT 'comment_history.comment_id',
-  flapping_history_id binary(16) NULL DEFAULT NULL COMMENT 'flapping_history.id',
-  acknowledgement_history_id binary(16) NULL DEFAULT NULL COMMENT 'acknowledgement_history.id',
+  flapping_history_id binary(20) NULL DEFAULT NULL COMMENT 'flapping_history.id',
+  acknowledgement_history_id binary(20) NULL DEFAULT NULL COMMENT 'acknowledgement_history.id',
 
   event_type enum('notification','state_change','downtime_schedule','downtime_start', 'downtime_end','comment_add','comment_remove','flapping_start','flapping_end','ack_set','ack_clear') NOT NULL,
   event_time bigint(20) unsigned NOT NULL,
diff --git a/utils/convert.go b/utils/convert.go
index d4ca2eed..ed1de9fe 100644
--- a/utils/convert.go
+++ b/utils/convert.go
@@ -144,3 +144,12 @@ func TimeToFloat(t time.Time) float64 {
 	secs := t.Unix()
 	return float64(secs) + float64(t.Sub(time.Unix(secs, 0)))/float64(time.Second)
 }
+
+// DefaultIfNil returns a defaultValue, if the given value is nil
+func DefaultIfNil(value, defaultValue interface{}) interface{} {
+	if value != nil {
+		return value
+	} else {
+		return defaultValue
+	}
+}
\ No newline at end of file