diff options
Diffstat (limited to 'db/migrate/20170920024819_status_ids_to_timestamp_ids.rb')
-rw-r--r-- | db/migrate/20170920024819_status_ids_to_timestamp_ids.rb | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/db/migrate/20170920024819_status_ids_to_timestamp_ids.rb b/db/migrate/20170920024819_status_ids_to_timestamp_ids.rb new file mode 100644 index 000000000..5d15817bd --- /dev/null +++ b/db/migrate/20170920024819_status_ids_to_timestamp_ids.rb @@ -0,0 +1,32 @@ +class StatusIdsToTimestampIds < ActiveRecord::Migration[5.1] + def up + # Prepare the function we will use to generate IDs. + Rake::Task['db:define_timestamp_id'].execute + + # Set up the statuses.id column to use our timestamp-based IDs. + ActiveRecord::Base.connection.execute(<<~SQL) + ALTER TABLE statuses + ALTER COLUMN id + SET DEFAULT timestamp_id('statuses') + SQL + + # Make sure we have a sequence to use. + Rake::Task['db:ensure_id_sequences_exist'].execute + end + + def down + # Revert the column to the old method of just using the sequence + # value for new IDs. Set the current ID sequence to the maximum + # existing ID, such that the next sequence will be one higher. + + # We lock the table during this so that the ID won't get clobbered, + # but ID is indexed, so this should be a fast operation. + ActiveRecord::Base.connection.execute(<<~SQL) + LOCK statuses; + SELECT setval('statuses_id_seq', (SELECT MAX(id) FROM statuses)); + ALTER TABLE statuses + ALTER COLUMN id + SET DEFAULT nextval('statuses_id_seq');" + SQL + end +end |