Add database upgrade file 43

etc/db/upgrades/upgrade43-v0.6.5-add-comparisons-notification-channel.sql

@@ -0,0 +1,96 @@
+-- Add procedure to decimate old nav data
+--
+-- New schema version: 0.6.5
+--
+-- ATTENTION:
+--
+-- ENSURE YOU HAVE BACKED UP THE DATABASE BEFORE RUNNING THIS SCRIPT.
+--
+--
+-- NOTE: This upgrade affects the public schema only.
+-- NOTE: Each application starts a transaction, which must be committed
+-- or rolled back.
+--
+-- This update modifies notify() to accept, as optional arguments, the
+-- names of columns that are to be *excluded* from the notification.
+-- It is intended for tables with large columns which are however of
+-- no particular interest in a notification.
+--
+-- To apply, run as the dougal user:
+--
+-- psql <<EOF
+-- \i $THIS_FILE
+-- COMMIT;
+-- EOF
+--
+-- NOTE: It can be applied multiple times without ill effect.
+--
+
+BEGIN;
+
+CREATE OR REPLACE PROCEDURE pg_temp.show_notice (notice text) AS $$
+BEGIN
+	RAISE NOTICE '%', notice;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE PROCEDURE pg_temp.upgrade_database () AS $outer$
+BEGIN
+
+	RAISE NOTICE 'Updating schema %', 'public';
+	SET search_path TO public;
+
+	-- BEGIN
+
+	CREATE OR REPLACE TRIGGER comparisons_tg
+		AFTER INSERT OR DELETE OR UPDATE
+		ON comparisons.comparisons
+		FOR EACH ROW
+		EXECUTE FUNCTION public.notify('comparisons', 'data');
+
+	-- END
+
+END;
+$outer$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE PROCEDURE pg_temp.upgrade () AS $outer$
+DECLARE
+	row RECORD;
+	current_db_version TEXT;
+BEGIN
+
+	SELECT value->>'db_schema' INTO current_db_version FROM public.info WHERE key = 'version';
+
+	IF current_db_version >= '0.6.5' THEN
+		RAISE EXCEPTION
+			USING MESSAGE='Patch already applied';
+	END IF;
+
+	IF current_db_version != '0.6.4' THEN
+		RAISE EXCEPTION
+			USING MESSAGE='Invalid database version: ' || current_db_version,
+				HINT='Ensure all previous patches have been applied.';
+	END IF;
+
+	CALL pg_temp.upgrade_database();
+END;
+$outer$ LANGUAGE plpgsql;
+
+CALL pg_temp.upgrade();
+
+CALL pg_temp.show_notice('Cleaning up');
+DROP PROCEDURE pg_temp.upgrade_database ();
+DROP PROCEDURE pg_temp.upgrade ();
+
+CALL pg_temp.show_notice('Updating db_schema version');
+INSERT INTO public.info VALUES ('version', '{"db_schema": "0.6.5"}')
+ON CONFLICT (key) DO UPDATE
+	SET value = public.info.value || '{"db_schema": "0.6.5"}' WHERE public.info.key = 'version';
+
+
+CALL pg_temp.show_notice('All done. You may now run "COMMIT;" to persist the changes');
+DROP PROCEDURE pg_temp.show_notice (notice text);
+
+--
+--NOTE Run `COMMIT;` now if all went well
+--