Add a couple of information/commands on the migration.sql

Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>

scripts/migration.sql

@@ -1,3 +1,5 @@
+\timing on
+
 -- Update the current messages table so it stores the year that we'll partition
 -- on.
 
@@ -5,6 +7,8 @@ ALTER TABLE messages ADD COLUMN year integer;
 update messages set year = extract(year from timestamp);
 
 
+-- Schema extracted using:
+-- sudo -u postgres pg_dump -t 'public.messages' --schema-only datanommer
 
 -- Create the messages2 table that will be partitioned and will have the messages
 -- moved to