db script for events

The commit adds a new table called Events.
It also adds a trigger to watch for changes in the events table and
send notifications to the events_channel.

Signed-off-by: Gaurav Gahlot <gauravgahlot0107@gmail.com>

deploy/db/tinkerbell-init.sql

@@ -74,3 +74,29 @@ CREATE TABLE IF NOT EXISTS workflow_data (
         , metadata JSONB
         , data JSONB
 );
+
+CREATE TABLE IF NOT EXISTS events (
+	id UUID UNIQUE NOT NULL primary key
+	, resource_id UUID NOT NULL
+	, resource_type int NOT NULL
+	, event_type int NOT NULL
+	, created_at TIMESTAMPTZ
+	, data JSONB
+);
+
+CREATE INDEX IF NOT EXISTS idx_eid ON events (id);
+CREATE INDEX IF NOT EXISTS idx_etype ON events (event_type);
+CREATE INDEX IF NOT EXISTS idx_rid ON events (resource_id);
+CREATE INDEX IF NOT EXISTS idx_rtype ON events (resource_type);
+
+CREATE OR REPLACE FUNCTION notify_event_changes()
+RETURNS trigger AS $$
+BEGIN
+  PERFORM pg_notify('events_channel', row_to_json(NEW)::text);
+  RETURN NULL;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER events_channel
+AFTER INSERT ON events
+FOR EACH ROW EXECUTE PROCEDURE notify_event_changes()