Schema: change sort order of history event type enum

schema/mysql/schema.sql

@@ -1269,7 +1269,15 @@ CREATE TABLE history (
   flapping_history_id binary(20) DEFAULT NULL COMMENT 'flapping_history.id',
   acknowledgement_history_id binary(20) DEFAULT NULL COMMENT 'acknowledgement_history.id',
 
-  event_type enum('notification','state_change','downtime_start', 'downtime_end','comment_add','comment_remove','flapping_start','flapping_end','ack_set','ack_clear') NOT NULL,
+  -- The enum values are ordered in a way that event_type provides a meaningful sort order for history entries with
+  -- the same event_time. state_change comes first as it can cause many of the other events like trigger downtimes,
+  -- remove acknowledgements and send notifications. Similarly, notification comes last as any other event can result
+  -- in a notification. End events sort before the corresponding start events as any ack/comment/downtime/flapping
+  -- period should last for more than a millisecond, therefore, the old period ends first and then the new one starts.
+  -- The remaining types are sorted by impact and cause: comments are informative, flapping is automatic and changes
+  -- mechanics, downtimes are semi-automatic, require user action (or configuration) and change mechanics, acks are pure
+  -- user actions and change mechanics.
+  event_type enum('state_change', 'ack_clear', 'downtime_end', 'flapping_end', 'comment_remove', 'comment_add', 'flapping_start', 'downtime_start', 'ack_set', 'notification') NOT NULL,
   event_time bigint unsigned NOT NULL,
 
   PRIMARY KEY (id),

schema/mysql/upgrades/1.2.0.sql

@@ -14,3 +14,17 @@ ALTER TABLE servicegroup
     ADD INDEX idx_servicegroup_name_ci (name_ci) COMMENT 'Servicegroup list filtered using quick search',
     DROP INDEX idx_servicegroup_name,
     ADD INDEX idx_servicegroup_name (name) COMMENT 'Host/service/service group list filtered by service group name; Servicegroup detail filter';
+
+-- The following sequence of statements changes the type of history.event_type like the following statement would:
+--
+--   ALTER TABLE history MODIFY event_type enum('state_change', 'ack_clear', 'downtime_end', 'flapping_end', 'comment_remove', 'comment_add', 'flapping_start', 'downtime_start', 'ack_set', 'notification') NOT NULL;
+--
+-- It's just much faster to add a second column, copy the column using an UPDATE statement and then replace the
+-- old column with the one just generated. Table locking ensures that no other connection inserts data in the meantime.
+LOCK TABLES history WRITE;
+ALTER TABLE history ADD COLUMN event_type_new enum('state_change', 'ack_clear', 'downtime_end', 'flapping_end', 'comment_remove', 'comment_add', 'flapping_start', 'downtime_start', 'ack_set', 'notification') NOT NULL AFTER event_type;
+UPDATE history SET event_type_new = event_type;
+ALTER TABLE history
+    DROP COLUMN event_type,
+    CHANGE COLUMN event_type_new event_type enum('state_change', 'ack_clear', 'downtime_end', 'flapping_end', 'comment_remove', 'comment_add', 'flapping_start', 'downtime_start', 'ack_set', 'notification') NOT NULL;
+UNLOCK TABLES;

schema/pgsql/schema.sql

@@ -19,7 +19,16 @@ CREATE TYPE state_type AS ENUM ( 'hard', 'soft' );
 CREATE TYPE checkable_type AS ENUM ( 'host', 'service' );
 CREATE TYPE comment_type AS ENUM ( 'comment', 'ack' );
 CREATE TYPE notification_type AS ENUM ( 'downtime_start', 'downtime_end', 'downtime_removed', 'custom', 'acknowledgement', 'problem', 'recovery', 'flapping_start', 'flapping_end' );
-CREATE TYPE history_type AS ENUM ( 'notification', 'state_change', 'downtime_start', 'downtime_end', 'comment_add', 'comment_remove', 'flapping_start', 'flapping_end', 'ack_set', 'ack_clear' );
+
+-- The enum values are ordered in a way that event_type provides a meaningful sort order for history entries with
+-- the same event_time. state_change comes first as it can cause many of the other events like trigger downtimes,
+-- remove acknowledgements and send notifications. Similarly, notification comes last as any other event can result
+-- in a notification. End events sort before the corresponding start events as any ack/comment/downtime/flapping
+-- period should last for more than a millisecond, therefore, the old period ends first and then the new one starts.
+-- The remaining types are sorted by impact and cause: comments are informative, flapping is automatic and changes
+-- mechanics, downtimes are semi-automatic, require user action (or configuration) and change mechanics, acks are pure
+-- user actions and change mechanics.
+CREATE TYPE history_type AS ENUM ( 'state_change', 'ack_clear', 'downtime_end', 'flapping_end', 'comment_remove', 'comment_add', 'flapping_start', 'downtime_start', 'ack_set', 'notification' );
 
 CREATE OR REPLACE FUNCTION get_sla_ok_percent(
   in_host_id bytea20,
@@ -2040,7 +2049,7 @@ CREATE TABLE history (
   flapping_history_id bytea20 DEFAULT NULL,
   acknowledgement_history_id bytea20 DEFAULT NULL,
 
-  event_type history_type NOT NULL DEFAULT 'notification',
+  event_type history_type NOT NULL DEFAULT 'state_change',
   event_time biguint NOT NULL,
 
   CONSTRAINT pk_history PRIMARY KEY (id),

schema/pgsql/upgrades/1.2.0.sql

@@ -14,3 +14,11 @@ CREATE INDEX idx_servicegroup_name_ci ON servicegroup(name_ci);
 COMMENT ON INDEX idx_servicegroup_display_name IS 'Servicegroup list filtered/ordered by display_name';
 COMMENT ON INDEX idx_servicegroup_name_ci IS 'Servicegroup list filtered using quick search';
 COMMENT ON INDEX idx_servicegroup_name IS 'Host/service/service group list filtered by service group name; Servicegroup detail filter';
+
+ALTER TYPE history_type RENAME TO history_type_old;
+CREATE TYPE history_type AS ENUM ( 'state_change', 'ack_clear', 'downtime_end', 'flapping_end', 'comment_remove', 'comment_add', 'flapping_start', 'downtime_start', 'ack_set', 'notification' );
+ALTER TABLE history
+  ALTER COLUMN event_type DROP DEFAULT,
+  ALTER COLUMN event_type TYPE history_type USING event_type::text::history_type,
+  ALTER COLUMN event_type SET DEFAULT 'state_change'::history_type;
+DROP TYPE history_type_old;