adding indexed created_at column to lineage events table (#2299)

* adding indexed created_at column to lineage events table

Signed-off-by: Prachi Mishra <prachi.mishra@astronomer.io>

* populate default values in lineage_events.created_at column

Signed-off-by: Prachi Mishra <prachi.mishra@astronomer.io>

* removing backfill step

Signed-off-by: Prachi Mishra <prachi.mishra@astronomer.io>

* altering type to TIMESTAMP WITH TIME ZONE

Signed-off-by: Prachi Mishra <prachi.mishra@astronomer.io>

* adding NULLS LAST in desc index on lineage_events.created_at

Signed-off-by: Prachi Mishra <prachi.mishra@astronomer.io>

Signed-off-by: Prachi Mishra <prachi.mishra@astronomer.io>

api/src/main/resources/marquez/db/migration/V54__lineage_events_created_at_indexed.sql

@@ -0,0 +1,7 @@
+-- new column will be created with 'null' filled for existing rows
+ALTER TABLE lineage_events ADD created_at TIMESTAMP WITH TIME ZONE;
+
+create index lineage_events_created_at_index on lineage_events (created_at desc NULLS LAST);
+
+-- The new default set to UTC now() will only apply in subsequent INSERT or UPDATE commands; it does not cause rows already in the table to change.
+ALTER TABLE lineage_events ALTER COLUMN created_at SET DEFAULT (now() AT TIME ZONE 'UTC')::timestamptz;